* [PATCH] ceph: fix OOB read in ceph_osdc_list_watchers via uncapped outdata_len
@ 2026-05-22 18:02 Pavitra Jha
2026-05-26 18:45 ` Viacheslav Dubeyko
0 siblings, 1 reply; 10+ messages in thread
From: Pavitra Jha @ 2026-05-22 18:02 UTC (permalink / raw)
To: idryomov; +Cc: amarkuze, slava, ceph-devel, linux-kernel, stable, Pavitra Jha
The OSD reply header field op->payload_len is wire-controlled and is
copied directly into m->outdata_len[i] without any bounds check:
m->outdata_len[i] = le32_to_cpu(op->payload_len);
This value propagates unchecked to req->r_ops[0].outdata_len and is
then used to set the decode boundary in ceph_osdc_list_watchers():
void *const end = p + req->r_ops[0].outdata_len;
The actual data allocation is always exactly one page:
ceph_alloc_page_vector(1, GFP_NOIO)
ceph_osd_data_pages_init(..., PAGE_SIZE, ...)
The messenger caps the copy to PAGE_SIZE bytes, but the decode window
end is set from the uncapped wire value. A malicious OSD can send
outdata_len=0x10000, causing _safe decoder boundary checks to pass
while the physical reads cross the slab allocation boundary.
KASAN report (kernel 7.0.0-rc7, QEMU/x86_64, KASLR disabled):
==================================================================
BUG: KASAN: slab-out-of-bounds in ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc]
Read of size 4 at addr ffff88800a229f9e by task insmod/57
CPU: 0 UID: 0 PID: 57 Comm: insmod Tainted: G O 7.0.0-rc7-g9c2abf69da83-dirty #15 PREEMPT(lazy)
Tainted: [O]=OOT_MODULE
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x4d/0x70
print_report+0x170/0x4f3
? __pfx__raw_spin_lock_irqsave+0x10/0x10
kasan_report+0xda/0x110
? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc]
? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc]
? __pfx_ceph_oob2_init+0x10/0x10 [ceph_oob2_poc]
ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc]
do_one_initcall+0x9a/0x3a0
? __pfx_do_one_initcall+0x10/0x10
? kasan_unpoison+0x44/0x70
do_init_module+0x27c/0x790
? __pfx_do_init_module+0x10/0x10
? __kasan_slab_free+0x47/0x70
? kfree+0x15f/0x3b0
load_module+0x4a9a/0x6350
? __pfx_load_module+0x10/0x10
? security_file_permission+0x24/0x50
? kernel_read_file+0x2ed/0x770
? init_module_from_file+0x15c/0x180
init_module_from_file+0x15c/0x180
? __pfx_init_module_from_file+0x10/0x10
? tick_nohz_handler+0x2a3/0x640
? _raw_spin_lock+0x7e/0xd0
idempotent_init_module+0x21f/0x750
? __pfx_idempotent_init_module+0x10/0x10
? fdget+0x4e/0x4a0
? fdget+0x4e/0x4a0
__x64_sys_finit_module+0xba/0x120
do_syscall_64+0xe2/0x570
? exc_page_fault+0x66/0xb0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Allocated by task 57:
kasan_save_stack+0x30/0x50
kasan_save_track+0x14/0x30
__kasan_kmalloc+0x7f/0x90
ceph_oob2_init+0x44/0xff0 [ceph_oob2_poc]
do_one_initcall+0x9a/0x3a0
do_init_module+0x27c/0x790
load_module+0x4a9a/0x6350
init_module_from_file+0x15c/0x180
idempotent_init_module+0x21f/0x750
__x64_sys_finit_module+0xba/0x120
do_syscall_64+0xe2/0x570
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff88800a229000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 3998 bytes inside of
allocated 4000-byte region [ffff88800a229000, ffff88800a229fa0)
Memory state around the buggy address:
ffff88800a229e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88800a229f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88800a229f80: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff88800a22a000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88800a22a080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
val=0xccccaaaa (OOB garbage from KASAN redzone)
Fix by capping the decode window end to PAGE_SIZE, matching the
actual allocation size.
Attacker model: a malicious or compromised OSD in a multi-tenant
Ceph deployment can trigger this against any client issuing
CEPH_OSD_OP_LIST_WATCHERS without further privileges beyond OSD
session establishment.
Fixes: a4ed38d7a180 ("libceph: support for CEPH_OSD_OP_LIST_WATCHERS")
Cc: stable@vger.kernel.org
Signed-off-by: Pavitra Jha <jhapavitra98@gmail.com>
---
net/ceph/osd_client.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 0148e4c40..a67093cf4 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -5091,7 +5091,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc,
ret = ceph_osdc_wait_request(osdc, req);
if (ret >= 0) {
void *p = page_address(pages[0]);
- void *const end = p + req->r_ops[0].outdata_len;
+ void *const end = p + min_t(u32, req->r_ops[0].outdata_len, PAGE_SIZE);
ret = decode_watchers(&p, end, watchers, num_watchers);
}
--
2.53.0
^ permalink raw reply related [flat|nested] 10+ messages in thread* Re: [PATCH] ceph: fix OOB read in ceph_osdc_list_watchers via uncapped outdata_len 2026-05-22 18:02 [PATCH] ceph: fix OOB read in ceph_osdc_list_watchers via uncapped outdata_len Pavitra Jha @ 2026-05-26 18:45 ` Viacheslav Dubeyko 2026-05-28 12:29 ` [PATCH v2] " Pavitra Jha 0 siblings, 1 reply; 10+ messages in thread From: Viacheslav Dubeyko @ 2026-05-26 18:45 UTC (permalink / raw) To: idryomov@gmail.com, jhapavitra98@gmail.com Cc: stable@vger.kernel.org, Alex Markuze, slava@dubeyko.com, linux-kernel@vger.kernel.org, ceph-devel@vger.kernel.org On Fri, 2026-05-22 at 14:02 -0400, Pavitra Jha wrote: > The OSD reply header field op->payload_len is wire-controlled and is > copied directly into m->outdata_len[i] without any bounds check: > > m->outdata_len[i] = le32_to_cpu(op->payload_len); > > This value propagates unchecked to req->r_ops[0].outdata_len and is > then used to set the decode boundary in ceph_osdc_list_watchers(): > > void *const end = p + req->r_ops[0].outdata_len; > > The actual data allocation is always exactly one page: > ceph_alloc_page_vector(1, GFP_NOIO) > ceph_osd_data_pages_init(..., PAGE_SIZE, ...) > > The messenger caps the copy to PAGE_SIZE bytes, but the decode window > end is set from the uncapped wire value. A malicious OSD can send > outdata_len=0x10000, causing _safe decoder boundary checks to pass > while the physical reads cross the slab allocation boundary. > > KASAN report (kernel 7.0.0-rc7, QEMU/x86_64, KASLR disabled): > ================================================================== > BUG: KASAN: slab-out-of-bounds in ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > Read of size 4 at addr ffff88800a229f9e by task insmod/57 > > CPU: 0 UID: 0 PID: 57 Comm: insmod Tainted: G O 7.0.0-rc7-g9c2abf69da83-dirty #15 PREEMPT(lazy) > Tainted: [O]=OOT_MODULE > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 > Call Trace: > <TASK> > dump_stack_lvl+0x4d/0x70 > print_report+0x170/0x4f3 > ? __pfx__raw_spin_lock_irqsave+0x10/0x10 > kasan_report+0xda/0x110 > ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > ? __pfx_ceph_oob2_init+0x10/0x10 [ceph_oob2_poc] > ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > do_one_initcall+0x9a/0x3a0 > ? __pfx_do_one_initcall+0x10/0x10 > ? kasan_unpoison+0x44/0x70 > do_init_module+0x27c/0x790 > ? __pfx_do_init_module+0x10/0x10 > ? __kasan_slab_free+0x47/0x70 > ? kfree+0x15f/0x3b0 > load_module+0x4a9a/0x6350 > ? __pfx_load_module+0x10/0x10 > ? security_file_permission+0x24/0x50 > ? kernel_read_file+0x2ed/0x770 > ? init_module_from_file+0x15c/0x180 > init_module_from_file+0x15c/0x180 > ? __pfx_init_module_from_file+0x10/0x10 > ? tick_nohz_handler+0x2a3/0x640 > ? _raw_spin_lock+0x7e/0xd0 > idempotent_init_module+0x21f/0x750 > ? __pfx_idempotent_init_module+0x10/0x10 > ? fdget+0x4e/0x4a0 > ? fdget+0x4e/0x4a0 > __x64_sys_finit_module+0xba/0x120 > do_syscall_64+0xe2/0x570 > ? exc_page_fault+0x66/0xb0 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Allocated by task 57: > kasan_save_stack+0x30/0x50 > kasan_save_track+0x14/0x30 > __kasan_kmalloc+0x7f/0x90 > ceph_oob2_init+0x44/0xff0 [ceph_oob2_poc] > do_one_initcall+0x9a/0x3a0 > do_init_module+0x27c/0x790 > load_module+0x4a9a/0x6350 > init_module_from_file+0x15c/0x180 > idempotent_init_module+0x21f/0x750 > __x64_sys_finit_module+0xba/0x120 > do_syscall_64+0xe2/0x570 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > The buggy address belongs to the object at ffff88800a229000 > which belongs to the cache kmalloc-4k of size 4096 > The buggy address is located 3998 bytes inside of > allocated 4000-byte region [ffff88800a229000, ffff88800a229fa0) > > Memory state around the buggy address: > ffff88800a229e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > ffff88800a229f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > >ffff88800a229f80: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc > ^ > ffff88800a22a000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff88800a22a080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ================================================================== > > val=0xccccaaaa (OOB garbage from KASAN redzone) > > Fix by capping the decode window end to PAGE_SIZE, matching the > actual allocation size. > > Attacker model: a malicious or compromised OSD in a multi-tenant > Ceph deployment can trigger this against any client issuing > CEPH_OSD_OP_LIST_WATCHERS without further privileges beyond OSD > session establishment. > > Fixes: a4ed38d7a180 ("libceph: support for CEPH_OSD_OP_LIST_WATCHERS") > Cc: stable@vger.kernel.org > Signed-off-by: Pavitra Jha <jhapavitra98@gmail.com> > --- > net/ceph/osd_client.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c > index 0148e4c40..a67093cf4 100644 > --- a/net/ceph/osd_client.c > +++ b/net/ceph/osd_client.c > @@ -5091,7 +5091,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, > ret = ceph_osdc_wait_request(osdc, req); > if (ret >= 0) { > void *p = page_address(pages[0]); > - void *const end = p + req->r_ops[0].outdata_len; > + void *const end = p + min_t(u32, req->r_ops[0].outdata_len, PAGE_SIZE); We cannot do assumption about the buffer size. Currently, it looks like a hardcoded value. Potentially, the buffer size could change and it could be the bug reason. We need to introduce a variable that should keep PAGE_SIZE value and it can be used in ceph_osd_data_pages_init(..., PAGE_SIZE, ...) and in min_t(u32, req- >r_ops[0].outdata_len, PAGE_SIZE). Thanks, Slava. > > ret = decode_watchers(&p, end, watchers, num_watchers); > } ^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v2] ceph: fix OOB read in ceph_osdc_list_watchers via uncapped outdata_len 2026-05-26 18:45 ` Viacheslav Dubeyko @ 2026-05-28 12:29 ` Pavitra Jha 2026-05-28 18:18 ` Viacheslav Dubeyko 0 siblings, 1 reply; 10+ messages in thread From: Pavitra Jha @ 2026-05-28 12:29 UTC (permalink / raw) To: idryomov, Slava.Dubeyko; +Cc: ceph-devel, linux-kernel, stable, Pavitra Jha The OSD reply header field op->payload_len is wire-controlled and is copied directly into m->outdata_len[i] without any bounds check: m->outdata_len[i] = le32_to_cpu(op->payload_len); This value propagates unchecked to req->r_ops[0].outdata_len and is then used to set the decode boundary in ceph_osdc_list_watchers(): void *const end = p + req->r_ops[0].outdata_len; The actual data allocation is always exactly one page: ceph_alloc_page_vector(1, GFP_NOIO) ceph_osd_data_pages_init(..., PAGE_SIZE, ...) The messenger caps the copy to PAGE_SIZE bytes, but the decode window end is set from the uncapped wire value. A malicious OSD can send outdata_len=0x10000, causing _safe decoder boundary checks to pass while the physical reads cross the slab allocation boundary. KASAN report (kernel 7.0.0-rc7, QEMU/x86_64, KASLR disabled): ================================================================== BUG: KASAN: slab-out-of-bounds in ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] Read of size 4 at addr ffff88800a229f9e by task insmod/57 CPU: 0 UID: 0 PID: 57 Comm: insmod Tainted: G O 7.0.0-rc7-g9c2abf69da83-dirty #15 PREEMPT(lazy) Tainted: [O]=OOT_MODULE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x4d/0x70 print_report+0x170/0x4f3 ? __pfx__raw_spin_lock_irqsave+0x10/0x10 kasan_report+0xda/0x110 ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] ? __pfx_ceph_oob2_init+0x10/0x10 [ceph_oob2_poc] ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] do_one_initcall+0x9a/0x3a0 ? __pfx_do_one_initcall+0x10/0x10 ? kasan_unpoison+0x44/0x70 do_init_module+0x27c/0x790 ? __pfx_do_init_module+0x10/0x10 ? __kasan_slab_free+0x47/0x70 ? kfree+0x15f/0x3b0 load_module+0x4a9a/0x6350 ? __pfx_load_module+0x10/0x10 ? security_file_permission+0x24/0x50 ? kernel_read_file+0x2ed/0x770 ? init_module_from_file+0x15c/0x180 init_module_from_file+0x15c/0x180 ? __pfx_init_module_from_file+0x10/0x10 ? tick_nohz_handler+0x2a3/0x640 ? _raw_spin_lock+0x7e/0xd0 idempotent_init_module+0x21f/0x750 ? __pfx_idempotent_init_module+0x10/0x10 ? fdget+0x4e/0x4a0 ? fdget+0x4e/0x4a0 __x64_sys_finit_module+0xba/0x120 do_syscall_64+0xe2/0x570 ? exc_page_fault+0x66/0xb0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated by task 57: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x7f/0x90 ceph_oob2_init+0x44/0xff0 [ceph_oob2_poc] do_one_initcall+0x9a/0x3a0 do_init_module+0x27c/0x790 load_module+0x4a9a/0x6350 init_module_from_file+0x15c/0x180 idempotent_init_module+0x21f/0x750 __x64_sys_finit_module+0xba/0x120 do_syscall_64+0xe2/0x570 entry_YSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88800a229000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 3998 bytes inside of allocated 4000-byte region [ffff88800a229000, ffff88800a229fa0) Memory state around the buggy address: ffff88800a229e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88800a229f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff88800a229f80: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff88800a22a000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88800a22a080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== val=0xccccaaaa (OOB garbage from KASAN redzone) Fix by introducing buf_len to hold the allocation size, using it in both ceph_osd_data_pages_init() and the min_t() decode boundary cap, so the two are guaranteed to stay in sync if the buffer size changes. Attacker model: a malicious or compromised OSD in a multi-tenant Ceph deployment can trigger this against any client issuing CEPH_OSD_OP_LIST_WATCHERS without further privileges beyond OSD session establishment. Fixes: a4ed38d7a180 ("libceph: support for CEPH_OSD_OP_LIST_WATCHERS") Cc: stable@vger.kernel.org Signed-off-by: Pavitra Jha <jhapavitra98@gmail.com> --- v2: Introduce buf_len variable instead of hardcoding PAGE_SIZE independently in ceph_osd_data_pages_init() and the min_t() cap, per Viacheslav Dubeyko's review. --- net/ceph/osd_client.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c index a67093cf4..7545d3608 100644 --- a/net/ceph/osd_client.c +++ b/net/ceph/osd_client.c @@ -5063,6 +5063,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, struct ceph_osd_request *req; struct page **pages; int ret; + const size_t buf_len = PAGE_SIZE; req = ceph_osdc_alloc_request(osdc, NULL, 1, false, GFP_NOIO); if (!req) @@ -5081,7 +5082,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, osd_req_op_init(req, 0, CEPH_OSD_OP_LIST_WATCHERS, 0); ceph_osd_data_pages_init(osd_req_op_data(req, 0, list_watchers, response_data), - pages, PAGE_SIZE, 0, false, true); + pages, buf_len, 0, false, true); ret = ceph_osdc_alloc_messages(req, GFP_NOIO); if (ret) @@ -5091,7 +5092,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, ret = ceph_osdc_wait_request(osdc, req); if (ret >= 0) { void *p = page_address(pages[0]); - void *const end = p + min_t(u32, req->r_ops[0].outdata_len, PAGE_SIZE); + void *const end = p + min_t(u32, req->r_ops[0].outdata_len, buf_len); ret = decode_watchers(&p, end, watchers, num_watchers); } -- 2.53.0 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH v2] ceph: fix OOB read in ceph_osdc_list_watchers via uncapped outdata_len 2026-05-28 12:29 ` [PATCH v2] " Pavitra Jha @ 2026-05-28 18:18 ` Viacheslav Dubeyko 2026-06-02 4:54 ` [PATCH v3] " Pavitra Jha 0 siblings, 1 reply; 10+ messages in thread From: Viacheslav Dubeyko @ 2026-05-28 18:18 UTC (permalink / raw) To: idryomov@gmail.com, jhapavitra98@gmail.com Cc: ceph-devel@vger.kernel.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org On Thu, 2026-05-28 at 08:29 -0400, Pavitra Jha wrote: > The OSD reply header field op->payload_len is wire-controlled and is > copied directly into m->outdata_len[i] without any bounds check: > > m->outdata_len[i] = le32_to_cpu(op->payload_len); > > This value propagates unchecked to req->r_ops[0].outdata_len and is > then used to set the decode boundary in ceph_osdc_list_watchers(): > > void *const end = p + req->r_ops[0].outdata_len; > > The actual data allocation is always exactly one page: > ceph_alloc_page_vector(1, GFP_NOIO) > ceph_osd_data_pages_init(..., PAGE_SIZE, ...) > > The messenger caps the copy to PAGE_SIZE bytes, but the decode window > end is set from the uncapped wire value. A malicious OSD can send > outdata_len=0x10000, causing _safe decoder boundary checks to pass > while the physical reads cross the slab allocation boundary. > > KASAN report (kernel 7.0.0-rc7, QEMU/x86_64, KASLR disabled): > > ================================================================== > BUG: KASAN: slab-out-of-bounds in ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > Read of size 4 at addr ffff88800a229f9e by task insmod/57 > > CPU: 0 UID: 0 PID: 57 Comm: insmod Tainted: G O 7.0.0-rc7-g9c2abf69da83-dirty #15 PREEMPT(lazy) > Tainted: [O]=OOT_MODULE > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 > Call Trace: > <TASK> > dump_stack_lvl+0x4d/0x70 > print_report+0x170/0x4f3 > ? __pfx__raw_spin_lock_irqsave+0x10/0x10 > kasan_report+0xda/0x110 > ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > ? __pfx_ceph_oob2_init+0x10/0x10 [ceph_oob2_poc] > ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > do_one_initcall+0x9a/0x3a0 > ? __pfx_do_one_initcall+0x10/0x10 > ? kasan_unpoison+0x44/0x70 > do_init_module+0x27c/0x790 > ? __pfx_do_init_module+0x10/0x10 > ? __kasan_slab_free+0x47/0x70 > ? kfree+0x15f/0x3b0 > load_module+0x4a9a/0x6350 > ? __pfx_load_module+0x10/0x10 > ? security_file_permission+0x24/0x50 > ? kernel_read_file+0x2ed/0x770 > ? init_module_from_file+0x15c/0x180 > init_module_from_file+0x15c/0x180 > ? __pfx_init_module_from_file+0x10/0x10 > ? tick_nohz_handler+0x2a3/0x640 > ? _raw_spin_lock+0x7e/0xd0 > idempotent_init_module+0x21f/0x750 > ? __pfx_idempotent_init_module+0x10/0x10 > ? fdget+0x4e/0x4a0 > ? fdget+0x4e/0x4a0 > __x64_sys_finit_module+0xba/0x120 > do_syscall_64+0xe2/0x570 > ? exc_page_fault+0x66/0xb0 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Allocated by task 57: > kasan_save_stack+0x30/0x50 > kasan_save_track+0x14/0x30 > __kasan_kmalloc+0x7f/0x90 > ceph_oob2_init+0x44/0xff0 [ceph_oob2_poc] > do_one_initcall+0x9a/0x3a0 > do_init_module+0x27c/0x790 > load_module+0x4a9a/0x6350 > init_module_from_file+0x15c/0x180 > idempotent_init_module+0x21f/0x750 > __x64_sys_finit_module+0xba/0x120 > do_syscall_64+0xe2/0x570 > entry_YSCALL_64_after_hwframe+0x77/0x7f > > The buggy address belongs to the object at ffff88800a229000 > which belongs to the cache kmalloc-4k of size 4096 > The buggy address is located 3998 bytes inside of > allocated 4000-byte region [ffff88800a229000, ffff88800a229fa0) > > Memory state around the buggy address: > ffff88800a229e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > ffff88800a229f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > >ffff88800a229f80: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc > ^ > ffff88800a22a000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff88800a22a080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ================================================================== > > val=0xccccaaaa (OOB garbage from KASAN redzone) > > Fix by introducing buf_len to hold the allocation size, using it in > both ceph_osd_data_pages_init() and the min_t() decode boundary cap, > so the two are guaranteed to stay in sync if the buffer size changes. > > Attacker model: a malicious or compromised OSD in a multi-tenant > Ceph deployment can trigger this against any client issuing > CEPH_OSD_OP_LIST_WATCHERS without further privileges beyond OSD > session establishment. > > Fixes: a4ed38d7a180 ("libceph: support for CEPH_OSD_OP_LIST_WATCHERS") > Cc: stable@vger.kernel.org > Signed-off-by: Pavitra Jha <jhapavitra98@gmail.com> > --- > v2: Introduce buf_len variable instead of hardcoding PAGE_SIZE > independently in ceph_osd_data_pages_init() and the min_t() cap, > per Viacheslav Dubeyko's review. > --- > net/ceph/osd_client.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c > index a67093cf4..7545d3608 100644 > --- a/net/ceph/osd_client.c > +++ b/net/ceph/osd_client.c > @@ -5063,6 +5063,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, > struct ceph_osd_request *req; > struct page **pages; > int ret; > + const size_t buf_len = PAGE_SIZE; > > req = ceph_osdc_alloc_request(osdc, NULL, 1, false, GFP_NOIO); > if (!req) > @@ -5081,7 +5082,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, > osd_req_op_init(req, 0, CEPH_OSD_OP_LIST_WATCHERS, 0); > ceph_osd_data_pages_init(osd_req_op_data(req, 0, list_watchers, > response_data), > - pages, PAGE_SIZE, 0, false, true); > + pages, buf_len, 0, false, true); > > ret = ceph_osdc_alloc_messages(req, GFP_NOIO); > if (ret) > @@ -5091,7 +5092,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, > ret = ceph_osdc_wait_request(osdc, req); > if (ret >= 0) { > void *p = page_address(pages[0]); > - void *const end = p + min_t(u32, req->r_ops[0].outdata_len, PAGE_SIZE); > + void *const end = p + min_t(u32, req->r_ops[0].outdata_len, buf_len); This patch is not correctly prepared because initially the patch has this: - void *const end = p + req->r_ops[0].outdata_len; + void *const end = p + min_t(u32, req->r_ops[0].outdata_len, PAGE_SIZE); Also, this line has 85 symbols. This statement should be reworked to be not longer than 80 symbols. Thanks, Slava. > > ret = decode_watchers(&p, end, watchers, num_watchers); > } ^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v3] ceph: fix OOB read in ceph_osdc_list_watchers via uncapped outdata_len 2026-05-28 18:18 ` Viacheslav Dubeyko @ 2026-06-02 4:54 ` Pavitra Jha 2026-06-02 16:53 ` Viacheslav Dubeyko 0 siblings, 1 reply; 10+ messages in thread From: Pavitra Jha @ 2026-06-02 4:54 UTC (permalink / raw) To: idryomov, Slava.Dubeyko; +Cc: ceph-devel, linux-kernel, stable, Pavitra Jha The OSD reply header field op->payload_len is wire-controlled and is copied directly into m->outdata_len[i] without any bounds check: m->outdata_len[i] = le32_to_cpu(op->payload_len); This value propagates unchecked to req->r_ops[0].outdata_len and is then used to set the decode boundary in ceph_osdc_list_watchers(): void *const end = p + req->r_ops[0].outdata_len; The actual data allocation is always exactly one page: ceph_alloc_page_vector(1, GFP_NOIO) ceph_osd_data_pages_init(..., PAGE_SIZE, ...) The messenger caps the copy to PAGE_SIZE bytes, but the decode window end is set from the uncapped wire value. A malicious OSD can send outdata_len=0x10000, causing _safe decoder boundary checks to pass while the physical reads cross the slab allocation boundary. KASAN report (kernel 7.0.0-rc7, QEMU/x86_64, KASLR disabled): ================================================================== BUG: KASAN: slab-out-of-bounds in ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] Read of size 4 at addr ffff88800a229f9e by task insmod/57 CPU: 0 UID: 0 PID: 57 Comm: insmod Tainted: G O 7.0.0-rc7-g9c2abf69da83-dirty #15 PREEMPT(lazy) Tainted: [O]=OOT_MODULE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x4d/0x70 print_report+0x170/0x4f3 ? __pfx__raw_spin_lock_irqsave+0x10/0x10 kasan_report+0xda/0x110 ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] ? __pfx_ceph_oob2_init+0x10/0x10 [ceph_oob2_poc] ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] do_one_initcall+0x9a/0x3a0 ? __pfx_do_one_initcall+0x10/0x10 ? kasan_unpoison+0x44/0x70 do_init_module+0x27c/0x790 ? __pfx_do_init_module+0x10/0x10 ? __kasan_slab_free+0x47/0x70 ? kfree+0x15f/0x3b0 load_module+0x4a9a/0x6350 ? __pfx_load_module+0x10/0x10 ? security_file_permission+0x24/0x50 ? kernel_read_file+0x2ed/0x770 ? init_module_from_file+0x15c/0x180 init_module_from_file+0x15c/0x180 ? __pfx_init_module_from_file+0x10/0x10 ? tick_nohz_handler+0x2a3/0x640 ? _raw_spin_lock+0x7e/0xd0 idempotent_init_module+0x21f/0x750 ? __pfx_idempotent_init_module+0x10/0x10 ? fdget+0x4e/0x4a0 ? fdget+0x4e/0x4a0 __x64_sys_finit_module+0xba/0x120 do_syscall_64+0xe2/0x570 ? exc_page_fault+0x66/0xb0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated by task 57: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x7f/0x90 ceph_oob2_init+0x44/0xff0 [ceph_oob2_poc] do_one_initcall+0x9a/0x3a0 do_init_module+0x27c/0x790 load_module+0x4a9a/0x6350 init_module_from_file+0x15c/0x180 idempotent_init_module+0x21f/0x750 __x64_sys_finit_module+0xba/0x120 do_syscall_64+0xe2/0x570 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88800a229000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 3998 bytes inside of allocated 4000-byte region [ffff88800a229000, ffff88800a229fa0) Memory state around the buggy address: ffff88800a229e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88800a229f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff88800a229f80: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff88800a22a000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88800a22a080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== val=0xccccaaaa (OOB garbage from KASAN redzone) Fix by introducing buf_len to hold the allocation size, using it in both ceph_osd_data_pages_init() and the min_t() decode boundary cap, so the two are guaranteed to stay in sync if the buffer size changes. Attacker model: a malicious or compromised OSD in a multi-tenant Ceph deployment can trigger this against any client issuing CEPH_OSD_OP_LIST_WATCHERS without further privileges beyond OSD session establishment. Fixes: a4ed38d7a180 ("libceph: support for CEPH_OSD_OP_LIST_WATCHERS") Cc: stable@vger.kernel.org Signed-off-by: Pavitra Jha <jhapavitra98@gmail.com> --- v3: Split overlong min_t() line to fit 80-column limit, per Viacheslav Dubeyko's review of v2. v2: Introduce buf_len variable instead of hardcoding PAGE_SIZE independently in ceph_osd_data_pages_init() and the min_t() cap, per Viacheslav Dubeyko's review. --- net/ceph/osd_client.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c index a67093cf4..0a55bc1f9 100644 --- a/net/ceph/osd_client.c +++ b/net/ceph/osd_client.c @@ -5063,6 +5063,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, struct ceph_osd_request *req; struct page **pages; int ret; + const size_t buf_len = PAGE_SIZE; req = ceph_osdc_alloc_request(osdc, NULL, 1, false, GFP_NOIO); if (!req) @@ -5081,7 +5082,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, osd_req_op_init(req, 0, CEPH_OSD_OP_LIST_WATCHERS, 0); ceph_osd_data_pages_init(osd_req_op_data(req, 0, list_watchers, response_data), - pages, PAGE_SIZE, 0, false, true); + pages, buf_len, 0, false, true); ret = ceph_osdc_alloc_messages(req, GFP_NOIO); if (ret) @@ -5091,7 +5092,8 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, ret = ceph_osdc_wait_request(osdc, req); if (ret >= 0) { void *p = page_address(pages[0]); - void *const end = p + min_t(u32, req->r_ops[0].outdata_len, PAGE_SIZE); + void *const end = p + + min_t(u32, req->r_ops[0].outdata_len, buf_len); ret = decode_watchers(&p, end, watchers, num_watchers); } -- 2.53.0 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH v3] ceph: fix OOB read in ceph_osdc_list_watchers via uncapped outdata_len 2026-06-02 4:54 ` [PATCH v3] " Pavitra Jha @ 2026-06-02 16:53 ` Viacheslav Dubeyko 2026-06-09 5:00 ` Pavitra Jha 0 siblings, 1 reply; 10+ messages in thread From: Viacheslav Dubeyko @ 2026-06-02 16:53 UTC (permalink / raw) To: Pavitra Jha, idryomov, Slava.Dubeyko; +Cc: ceph-devel, linux-kernel, stable On Tue, 2026-06-02 at 00:54 -0400, Pavitra Jha wrote: > The OSD reply header field op->payload_len is wire-controlled and is > copied directly into m->outdata_len[i] without any bounds check: > > m->outdata_len[i] = le32_to_cpu(op->payload_len); > > This value propagates unchecked to req->r_ops[0].outdata_len and is > then used to set the decode boundary in ceph_osdc_list_watchers(): > > void *const end = p + req->r_ops[0].outdata_len; > > The actual data allocation is always exactly one page: > ceph_alloc_page_vector(1, GFP_NOIO) > ceph_osd_data_pages_init(..., PAGE_SIZE, ...) > > The messenger caps the copy to PAGE_SIZE bytes, but the decode window > end is set from the uncapped wire value. A malicious OSD can send > outdata_len=0x10000, causing _safe decoder boundary checks to pass > while the physical reads cross the slab allocation boundary. > > KASAN report (kernel 7.0.0-rc7, QEMU/x86_64, KASLR disabled): > > ================================================================== > BUG: KASAN: slab-out-of-bounds in ceph_oob2_init+0x23d/0xff0 > [ceph_oob2_poc] > Read of size 4 at addr ffff88800a229f9e by task insmod/57 > > CPU: 0 UID: 0 PID: 57 Comm: insmod Tainted: G O > 7.0.0-rc7-g9c2abf69da83-dirty #15 PREEMPT(lazy) > Tainted: [O]=OOT_MODULE > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0- > debian-1.17.0-1 04/01/2014 > Call Trace: > <TASK> > dump_stack_lvl+0x4d/0x70 > print_report+0x170/0x4f3 > ? __pfx__raw_spin_lock_irqsave+0x10/0x10 > kasan_report+0xda/0x110 > ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > ? __pfx_ceph_oob2_init+0x10/0x10 [ceph_oob2_poc] > ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > do_one_initcall+0x9a/0x3a0 > ? __pfx_do_one_initcall+0x10/0x10 > ? kasan_unpoison+0x44/0x70 > do_init_module+0x27c/0x790 > ? __pfx_do_init_module+0x10/0x10 > ? __kasan_slab_free+0x47/0x70 > ? kfree+0x15f/0x3b0 > load_module+0x4a9a/0x6350 > ? __pfx_load_module+0x10/0x10 > ? security_file_permission+0x24/0x50 > ? kernel_read_file+0x2ed/0x770 > ? init_module_from_file+0x15c/0x180 > init_module_from_file+0x15c/0x180 > ? __pfx_init_module_from_file+0x10/0x10 > ? tick_nohz_handler+0x2a3/0x640 > ? _raw_spin_lock+0x7e/0xd0 > idempotent_init_module+0x21f/0x750 > ? __pfx_idempotent_init_module+0x10/0x10 > ? fdget+0x4e/0x4a0 > ? fdget+0x4e/0x4a0 > __x64_sys_finit_module+0xba/0x120 > do_syscall_64+0xe2/0x570 > ? exc_page_fault+0x66/0xb0 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Allocated by task 57: > kasan_save_stack+0x30/0x50 > kasan_save_track+0x14/0x30 > __kasan_kmalloc+0x7f/0x90 > ceph_oob2_init+0x44/0xff0 [ceph_oob2_poc] > do_one_initcall+0x9a/0x3a0 > do_init_module+0x27c/0x790 > load_module+0x4a9a/0x6350 > init_module_from_file+0x15c/0x180 > idempotent_init_module+0x21f/0x750 > __x64_sys_finit_module+0xba/0x120 > do_syscall_64+0xe2/0x570 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > The buggy address belongs to the object at ffff88800a229000 > which belongs to the cache kmalloc-4k of size 4096 > The buggy address is located 3998 bytes inside of > allocated 4000-byte region [ffff88800a229000, ffff88800a229fa0) > > Memory state around the buggy address: > ffff88800a229e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > ffff88800a229f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > >ffff88800a229f80: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc > ^ > ffff88800a22a000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff88800a22a080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ================================================================== > > val=0xccccaaaa (OOB garbage from KASAN redzone) > > Fix by introducing buf_len to hold the allocation size, using it in > both ceph_osd_data_pages_init() and the min_t() decode boundary cap, > so the two are guaranteed to stay in sync if the buffer size changes. > > Attacker model: a malicious or compromised OSD in a multi-tenant > Ceph deployment can trigger this against any client issuing > CEPH_OSD_OP_LIST_WATCHERS without further privileges beyond OSD > session establishment. > > Fixes: a4ed38d7a180 ("libceph: support for > CEPH_OSD_OP_LIST_WATCHERS") > Cc: stable@vger.kernel.org > Signed-off-by: Pavitra Jha <jhapavitra98@gmail.com> > --- > v3: Split overlong min_t() line to fit 80-column limit, > per Viacheslav Dubeyko's review of v2. > v2: Introduce buf_len variable instead of hardcoding PAGE_SIZE > independently in ceph_osd_data_pages_init() and the min_t() cap, > per Viacheslav Dubeyko's review. > --- > net/ceph/osd_client.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c > index a67093cf4..0a55bc1f9 100644 > --- a/net/ceph/osd_client.c > +++ b/net/ceph/osd_client.c > @@ -5063,6 +5063,7 @@ int ceph_osdc_list_watchers(struct > ceph_osd_client *osdc, > struct ceph_osd_request *req; > struct page **pages; > int ret; > + const size_t buf_len = PAGE_SIZE; > > req = ceph_osdc_alloc_request(osdc, NULL, 1, false, > GFP_NOIO); > if (!req) > @@ -5081,7 +5082,7 @@ int ceph_osdc_list_watchers(struct > ceph_osd_client *osdc, > osd_req_op_init(req, 0, CEPH_OSD_OP_LIST_WATCHERS, 0); > ceph_osd_data_pages_init(osd_req_op_data(req, 0, > list_watchers, > response_data), > - pages, PAGE_SIZE, 0, false, true); > + pages, buf_len, 0, false, true); > > ret = ceph_osdc_alloc_messages(req, GFP_NOIO); > if (ret) > @@ -5091,7 +5092,8 @@ int ceph_osdc_list_watchers(struct > ceph_osd_client *osdc, > ret = ceph_osdc_wait_request(osdc, req); > if (ret >= 0) { > void *p = page_address(pages[0]); > - void *const end = p + min_t(u32, req- > >r_ops[0].outdata_len, PAGE_SIZE); > + void *const end = p + > + min_t(u32, req->r_ops[0].outdata_len, > buf_len); Now, min_t() worries me slightly because req->r_ops[0].outdata_len is u32 data type, but buf_len is size_t. Could we have the same data type for both variables? Thanks, Slava. > > ret = decode_watchers(&p, end, watchers, > num_watchers); > } ^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v3] ceph: fix OOB read in ceph_osdc_list_watchers via uncapped outdata_len 2026-06-02 16:53 ` Viacheslav Dubeyko @ 2026-06-09 5:00 ` Pavitra Jha 2026-06-11 4:14 ` Viacheslav Dubeyko 2026-07-02 11:40 ` [v3] " Alex Markuze 0 siblings, 2 replies; 10+ messages in thread From: Pavitra Jha @ 2026-06-09 5:00 UTC (permalink / raw) To: idryomov Cc: Slava.Dubeyko, amarkuze, ceph-devel, linux-kernel, Pavitra Jha, stable The OSD reply header field op->payload_len is wire-controlled and is copied directly into m->outdata_len[i] without any bounds check: m->outdata_len[i] = le32_to_cpu(op->payload_len); This value propagates unchecked to req->r_ops[0].outdata_len and is then used to set the decode boundary in ceph_osdc_list_watchers(): void *const end = p + req->r_ops[0].outdata_len; The actual data allocation is always exactly one page: ceph_alloc_page_vector(1, GFP_NOIO) ceph_osd_data_pages_init(..., PAGE_SIZE, ...) The messenger caps the copy to PAGE_SIZE bytes, but the decode window end is set from the uncapped wire value. A malicious OSD can send outdata_len=0x10000, causing _safe decoder boundary checks to pass while the physical reads cross the slab allocation boundary. KASAN report (kernel 7.0.0-rc7, QEMU/x86_64, KASLR disabled): ================================================================== BUG: KASAN: slab-out-of-bounds in ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] Read of size 4 at addr ffff88800a229f9e by task insmod/57 CPU: 0 UID: 0 PID: 57 Comm: insmod Tainted: G O 7.0.0-rc7-g9c2abf69da83-dirty #15 PREEMPT(lazy) Tainted: [O]=OOT_MODULE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x4d/0x70 print_report+0x170/0x4f3 ? __pfx__raw_spin_lock_irqsave+0x10/0x10 kasan_report+0xda/0x110 ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] ? __pfx_ceph_oob2_init+0x10/0x10 [ceph_oob2_poc] ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] do_one_initcall+0x9a/0x3a0 ? __pfx_do_one_initcall+0x10/0x10 ? kasan_unpoison+0x44/0x70 do_init_module+0x27c/0x790 ? __pfx_do_init_module+0x10/0x10 ? __kasan_slab_free+0x47/0x70 ? kfree+0x15f/0x3b0 load_module+0x4a9a/0x6350 ? __pfx_load_module+0x10/0x10 ? security_file_permission+0x24/0x50 ? kernel_read_file+0x2ed/0x770 ? init_module_from_file+0x15c/0x180 init_module_from_file+0x15c/0x180 ? __pfx_init_module_from_file+0x10/0x10 ? tick_nohz_handler+0x2a3/0x640 ? _raw_spin_lock+0x7e/0xd0 idempotent_init_module+0x21f/0x750 ? __pfx_idempotent_init_module+0x10/0x10 ? fdget+0x4e/0x4a0 ? fdget+0x4e/0x4a0 __x64_sys_finit_module+0xba/0x120 do_syscall_64+0xe2/0x570 ? exc_page_fault+0x66/0xb0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated by task 57: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x7f/0x90 ceph_oob2_init+0x44/0xff0 [ceph_oob2_poc] do_one_initcall+0x9a/0x3a0 do_init_module+0x27c/0x790 load_module+0x4a9a/0x6350 init_module_from_file+0x15c/0x180 idempotent_init_module+0x21f/0x750 __x64_sys_finit_module+0xba/0x120 do_syscall_64+0xe2/0x570 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88800a229000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 3998 bytes inside of allocated 4000-byte region [ffff88800a229000, ffff88800a229fa0) Memory state around the buggy address: ffff88800a229e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88800a229f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff88800a229f80: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff88800a22a000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88800a22a080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== val=0xccccaaaa (OOB garbage from KASAN redzone) Fix by introducing buf_len to hold the allocation size, using it in both ceph_osd_data_pages_init() and the min_t() decode boundary cap, so the two are guaranteed to stay in sync if the buffer size changes. buf_len is declared as u32 to match the type of outdata_len used in the min_t() expression. Attacker model: a malicious or compromised OSD in a multi-tenant Ceph deployment can trigger this against any client issuing CEPH_OSD_OP_LIST_WATCHERS without further privileges beyond OSD session establishment. Fixes: a4ed38d7a180 ("libceph: support for CEPH_OSD_OP_LIST_WATCHERS") Cc: stable@vger.kernel.org Signed-off-by: Pavitra Jha <jhapavitra98@gmail.com> --- v3: Change buf_len type from size_t to u32 to match outdata_len type in min_t(), per Viacheslav Dubeyko's review. v2: Introduce buf_len variable instead of hardcoding PAGE_SIZE independently in ceph_osd_data_pages_init() and the min_t() cap, per Viacheslav Dubeyko's review. --- net/ceph/osd_client.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c index a67093cf4..5ad47d932 100644 --- a/net/ceph/osd_client.c +++ b/net/ceph/osd_client.c @@ -5063,6 +5063,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, struct ceph_osd_request *req; struct page **pages; int ret; + const u32 buf_len = PAGE_SIZE; req = ceph_osdc_alloc_request(osdc, NULL, 1, false, GFP_NOIO); if (!req) @@ -5081,7 +5082,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, osd_req_op_init(req, 0, CEPH_OSD_OP_LIST_WATCHERS, 0); ceph_osd_data_pages_init(osd_req_op_data(req, 0, list_watchers, response_data), - pages, PAGE_SIZE, 0, false, true); + pages, buf_len, 0, false, true); ret = ceph_osdc_alloc_messages(req, GFP_NOIO); if (ret) @@ -5091,7 +5092,8 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, ret = ceph_osdc_wait_request(osdc, req); if (ret >= 0) { void *p = page_address(pages[0]); - void *const end = p + min_t(u32, req->r_ops[0].outdata_len, PAGE_SIZE); + void *const end = p + + min_t(u32, req->r_ops[0].outdata_len, buf_len); ret = decode_watchers(&p, end, watchers, num_watchers); } -- 2.53.0 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH v3] ceph: fix OOB read in ceph_osdc_list_watchers via uncapped outdata_len 2026-06-09 5:00 ` Pavitra Jha @ 2026-06-11 4:14 ` Viacheslav Dubeyko 2026-07-02 11:40 ` [v3] " Alex Markuze 1 sibling, 0 replies; 10+ messages in thread From: Viacheslav Dubeyko @ 2026-06-11 4:14 UTC (permalink / raw) To: Pavitra Jha, idryomov Cc: Slava.Dubeyko, amarkuze, ceph-devel, linux-kernel, stable On Tue, 2026-06-09 at 01:00 -0400, Pavitra Jha wrote: > The OSD reply header field op->payload_len is wire-controlled and is > copied directly into m->outdata_len[i] without any bounds check: > > m->outdata_len[i] = le32_to_cpu(op->payload_len); > > This value propagates unchecked to req->r_ops[0].outdata_len and is > then used to set the decode boundary in ceph_osdc_list_watchers(): > > void *const end = p + req->r_ops[0].outdata_len; > > The actual data allocation is always exactly one page: > ceph_alloc_page_vector(1, GFP_NOIO) > ceph_osd_data_pages_init(..., PAGE_SIZE, ...) > > The messenger caps the copy to PAGE_SIZE bytes, but the decode window > end is set from the uncapped wire value. A malicious OSD can send > outdata_len=0x10000, causing _safe decoder boundary checks to pass > while the physical reads cross the slab allocation boundary. > > KASAN report (kernel 7.0.0-rc7, QEMU/x86_64, KASLR disabled): > > ================================================================== > BUG: KASAN: slab-out-of-bounds in ceph_oob2_init+0x23d/0xff0 > [ceph_oob2_poc] > Read of size 4 at addr ffff88800a229f9e by task insmod/57 > > CPU: 0 UID: 0 PID: 57 Comm: insmod Tainted: G O > 7.0.0-rc7-g9c2abf69da83-dirty #15 PREEMPT(lazy) > Tainted: [O]=OOT_MODULE > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0- > debian-1.17.0-1 04/01/2014 > Call Trace: > <TASK> > dump_stack_lvl+0x4d/0x70 > print_report+0x170/0x4f3 > ? __pfx__raw_spin_lock_irqsave+0x10/0x10 > kasan_report+0xda/0x110 > ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > ? ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > ? __pfx_ceph_oob2_init+0x10/0x10 [ceph_oob2_poc] > ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] > do_one_initcall+0x9a/0x3a0 > ? __pfx_do_one_initcall+0x10/0x10 > ? kasan_unpoison+0x44/0x70 > do_init_module+0x27c/0x790 > ? __pfx_do_init_module+0x10/0x10 > ? __kasan_slab_free+0x47/0x70 > ? kfree+0x15f/0x3b0 > load_module+0x4a9a/0x6350 > ? __pfx_load_module+0x10/0x10 > ? security_file_permission+0x24/0x50 > ? kernel_read_file+0x2ed/0x770 > ? init_module_from_file+0x15c/0x180 > init_module_from_file+0x15c/0x180 > ? __pfx_init_module_from_file+0x10/0x10 > ? tick_nohz_handler+0x2a3/0x640 > ? _raw_spin_lock+0x7e/0xd0 > idempotent_init_module+0x21f/0x750 > ? __pfx_idempotent_init_module+0x10/0x10 > ? fdget+0x4e/0x4a0 > ? fdget+0x4e/0x4a0 > __x64_sys_finit_module+0xba/0x120 > do_syscall_64+0xe2/0x570 > ? exc_page_fault+0x66/0xb0 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Allocated by task 57: > kasan_save_stack+0x30/0x50 > kasan_save_track+0x14/0x30 > __kasan_kmalloc+0x7f/0x90 > ceph_oob2_init+0x44/0xff0 [ceph_oob2_poc] > do_one_initcall+0x9a/0x3a0 > do_init_module+0x27c/0x790 > load_module+0x4a9a/0x6350 > init_module_from_file+0x15c/0x180 > idempotent_init_module+0x21f/0x750 > __x64_sys_finit_module+0xba/0x120 > do_syscall_64+0xe2/0x570 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > The buggy address belongs to the object at ffff88800a229000 > which belongs to the cache kmalloc-4k of size 4096 > The buggy address is located 3998 bytes inside of > allocated 4000-byte region [ffff88800a229000, ffff88800a229fa0) > > Memory state around the buggy address: > ffff88800a229e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > ffff88800a229f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > >ffff88800a229f80: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc > ^ > ffff88800a22a000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff88800a22a080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ================================================================== > > val=0xccccaaaa (OOB garbage from KASAN redzone) > > Fix by introducing buf_len to hold the allocation size, using it in > both ceph_osd_data_pages_init() and the min_t() decode boundary cap, > so the two are guaranteed to stay in sync if the buffer size changes. > buf_len is declared as u32 to match the type of outdata_len used in > the min_t() expression. > > Attacker model: a malicious or compromised OSD in a multi-tenant > Ceph deployment can trigger this against any client issuing > CEPH_OSD_OP_LIST_WATCHERS without further privileges beyond OSD > session establishment. > > Fixes: a4ed38d7a180 ("libceph: support for > CEPH_OSD_OP_LIST_WATCHERS") > Cc: stable@vger.kernel.org > Signed-off-by: Pavitra Jha <jhapavitra98@gmail.com> > --- > v3: Change buf_len type from size_t to u32 to match outdata_len type > in min_t(), per Viacheslav Dubeyko's review. > v2: Introduce buf_len variable instead of hardcoding PAGE_SIZE > independently in ceph_osd_data_pages_init() and the min_t() cap, > per Viacheslav Dubeyko's review. > --- > net/ceph/osd_client.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c > index a67093cf4..5ad47d932 100644 > --- a/net/ceph/osd_client.c > +++ b/net/ceph/osd_client.c > @@ -5063,6 +5063,7 @@ int ceph_osdc_list_watchers(struct > ceph_osd_client *osdc, > struct ceph_osd_request *req; > struct page **pages; > int ret; > + const u32 buf_len = PAGE_SIZE; > > req = ceph_osdc_alloc_request(osdc, NULL, 1, false, > GFP_NOIO); > if (!req) > @@ -5081,7 +5082,7 @@ int ceph_osdc_list_watchers(struct > ceph_osd_client *osdc, > osd_req_op_init(req, 0, CEPH_OSD_OP_LIST_WATCHERS, 0); > ceph_osd_data_pages_init(osd_req_op_data(req, 0, > list_watchers, > response_data), > - pages, PAGE_SIZE, 0, false, true); > + pages, buf_len, 0, false, true); > > ret = ceph_osdc_alloc_messages(req, GFP_NOIO); > if (ret) > @@ -5091,7 +5092,8 @@ int ceph_osdc_list_watchers(struct > ceph_osd_client *osdc, > ret = ceph_osdc_wait_request(osdc, req); > if (ret >= 0) { > void *p = page_address(pages[0]); > - void *const end = p + min_t(u32, req- > >r_ops[0].outdata_len, PAGE_SIZE); > + void *const end = p + > + min_t(u32, req->r_ops[0].outdata_len, > buf_len); > > ret = decode_watchers(&p, end, watchers, > num_watchers); > } Looks good. Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com> Thanks, Slava. ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [v3] ceph: fix OOB read in ceph_osdc_list_watchers via uncapped outdata_len 2026-06-09 5:00 ` Pavitra Jha 2026-06-11 4:14 ` Viacheslav Dubeyko @ 2026-07-02 11:40 ` Alex Markuze 2026-07-07 10:57 ` [PATCH v4] " Pavitra Jha 1 sibling, 1 reply; 10+ messages in thread From: Alex Markuze @ 2026-07-02 11:40 UTC (permalink / raw) To: jhapavitra98; +Cc: Alex Markuze, ceph-devel Hi Pavitra, NACK for now: this patch does not apply cleanly to the current testing branch or linux/master. Please rebase and resend a new version. I tested it with `git am -3` against both trees, and both attempts failed. -- Alex Markuze ^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v4] ceph: fix OOB read in ceph_osdc_list_watchers via uncapped outdata_len 2026-07-02 11:40 ` [v3] " Alex Markuze @ 2026-07-07 10:57 ` Pavitra Jha 0 siblings, 0 replies; 10+ messages in thread From: Pavitra Jha @ 2026-07-07 10:57 UTC (permalink / raw) To: idryomov, amarkuze, slava; +Cc: ceph-devel, linux-kernel, stable, Pavitra Jha The OSD reply header field op->payload_len is wire-controlled and is copied directly into m->outdata_len[i] without any bounds check: m->outdata_len[i] = le32_to_cpu(op->payload_len); This value propagates unchecked to req->r_ops[0].outdata_len and is then used to set the decode boundary in ceph_osdc_list_watchers(): void *const end = p + req->r_ops[0].outdata_len; The actual data allocation is always exactly one page: ceph_alloc_page_vector(1, GFP_NOIO) ceph_osd_data_pages_init(..., PAGE_SIZE, ...) The messenger caps the copy to PAGE_SIZE bytes, but the decode window end is set from the uncapped wire value. A malicious OSD can send outdata_len=0x10000, causing _safe decoder boundary checks to pass while the physical reads cross the slab allocation boundary. KASAN report (kernel 7.0.0-rc7, QEMU/x86_64, KASLR disabled): ================================================================== BUG: KASAN: slab-out-of-bounds in ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] Read of size 4 at addr ffff88800a229f9e by task insmod/57 CPU: 0 UID: 0 PID: 57 Comm: insmod Tainted: G O 7.0.0-rc7-g9c2abf69da83-dirty #15 PREEMPT(lazy) Tainted: [O]=OOT_MODULE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x4d/0x70 print_report+0x170/0x4f3 kasan_report+0xda/0x110 ceph_oob2_init+0x23d/0xff0 [ceph_oob2_poc] do_one_initcall+0x9a/0x3a0 do_init_module+0x27c/0x790 load_module+0x4a9a/0x6350 init_module_from_file+0x15c/0x180 idempotent_init_module+0x21f/0x750 __x64_sys_finit_module+0xba/0x120 do_syscall_64+0xe2/0x570 entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated by task 57: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x7f/0x90 ceph_oob2_init+0x44/0xff0 [ceph_oob2_poc] do_one_initcall+0x9a/0x3a0 do_init_module+0x27c/0x790 load_module+0x4a9a/0x6350 init_module_from_file+0x15c/0x180 idempotent_init_module+0x21f/0x750 __x64_sys_finit_module+0xba/0x120 do_syscall_64+0xe2/0x570 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88800a229000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 3998 bytes inside of allocated 4000-byte region [ffff88800a229000, ffff88800a229fa0) Memory state around the buggy address: ffff88800a229e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88800a229f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff88800a229f80: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff88800a22a000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88800a22a080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== val=0xccccaaaa (OOB garbage from KASAN redzone) Fix by introducing buf_len to hold the allocation size, using it in both ceph_osd_data_pages_init() and the min_t() decode boundary cap, so the two are guaranteed to stay in sync if the buffer size changes. buf_len is declared as u32 to match the type of outdata_len used in the min_t() expression. Attacker model: a malicious or compromised OSD in a multi-tenant Ceph deployment can trigger this against any client issuing CEPH_OSD_OP_LIST_WATCHERS without further privileges beyond OSD session establishment. Fixes: a4ed38d7a180 ("libceph: support for CEPH_OSD_OP_LIST_WATCHERS") Cc: stable@vger.kernel.org Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com> Signed-off-by: Pavitra Jha <jhapavitra98@gmail.com> --- v4: Rebase against current linux/master and ceph-testing/testing, confirmed clean git am -3 apply against both. No functional changes from Slava's reviewed v3. v3: Change buf_len type from size_t to u32 to match outdata_len type in min_t(), per Viacheslav Dubeyko's review. v2: Introduce buf_len variable instead of hardcoding PAGE_SIZE independently in ceph_osd_data_pages_init() and the min_t() cap, per Viacheslav Dubeyko's review. --- net/ceph/osd_client.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c index 2ff00070c..62bec6ad8 100644 --- a/net/ceph/osd_client.c +++ b/net/ceph/osd_client.c @@ -5060,6 +5060,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, struct ceph_osd_request *req; struct page **pages; int ret; + const u32 buf_len = PAGE_SIZE; req = ceph_osdc_alloc_request(osdc, NULL, 1, false, GFP_NOIO); if (!req) @@ -5078,7 +5079,7 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, osd_req_op_init(req, 0, CEPH_OSD_OP_LIST_WATCHERS, 0); ceph_osd_data_pages_init(osd_req_op_data(req, 0, list_watchers, response_data), - pages, PAGE_SIZE, 0, false, true); + pages, buf_len, 0, false, true); ret = ceph_osdc_alloc_messages(req, GFP_NOIO); if (ret) @@ -5088,7 +5089,8 @@ int ceph_osdc_list_watchers(struct ceph_osd_client *osdc, ret = ceph_osdc_wait_request(osdc, req); if (ret >= 0) { void *p = page_address(pages[0]); - void *const end = p + req->r_ops[0].outdata_len; + void *const end = p + + min_t(u32, req->r_ops[0].outdata_len, buf_len); ret = decode_watchers(&p, end, watchers, num_watchers); } -- 2.53.0 ^ permalink raw reply related [flat|nested] 10+ messages in thread
end of thread, other threads:[~2026-07-07 10:58 UTC | newest] Thread overview: 10+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2026-05-22 18:02 [PATCH] ceph: fix OOB read in ceph_osdc_list_watchers via uncapped outdata_len Pavitra Jha 2026-05-26 18:45 ` Viacheslav Dubeyko 2026-05-28 12:29 ` [PATCH v2] " Pavitra Jha 2026-05-28 18:18 ` Viacheslav Dubeyko 2026-06-02 4:54 ` [PATCH v3] " Pavitra Jha 2026-06-02 16:53 ` Viacheslav Dubeyko 2026-06-09 5:00 ` Pavitra Jha 2026-06-11 4:14 ` Viacheslav Dubeyko 2026-07-02 11:40 ` [v3] " Alex Markuze 2026-07-07 10:57 ` [PATCH v4] " Pavitra Jha
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