[syzbot] [isofs?] KASAN: slab-out-of-bounds Read in isofs_fh_to_parent

[syzbot] [isofs?] KASAN: slab-out-of-bounds Read in isofs_fh_to_parent

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    a2392f333575 drm/panthor: Clean up FW version information ..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=16de47b0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8cceedf2e27e877d
dashboard link: https://syzkaller.appspot.com/bug?extid=4d7cd7dd0ce1aa8d5c65
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15a1ec3f980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17f623e4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7df8ceab3279/disk-a2392f33.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/42c5af403371/vmlinux-a2392f33.xz
kernel image: https://storage.googleapis.com/syzbot-assets/73599b849e20/Image-a2392f33.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/191f689db82e/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4d7cd7dd0ce1aa8d5c65@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 164
==================================================================
BUG: KASAN: slab-out-of-bounds in isofs_fh_to_parent+0x1b8/0x210 fs/isofs/export.c:183
Read of size 4 at addr ffff0000cc030d94 by task syz-executor215/6466

CPU: 1 UID: 0 PID: 6466 Comm: syz-executor215 Not tainted 6.14.0-rc7-syzkaller-ga2392f333575 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0x198/0x550 mm/kasan/report.c:521
 kasan_report+0xd8/0x138 mm/kasan/report.c:634
 __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
 isofs_fh_to_parent+0x1b8/0x210 fs/isofs/export.c:183
 exportfs_decode_fh_raw+0x2dc/0x608 fs/exportfs/expfs.c:523
 do_handle_to_path+0xa0/0x198 fs/fhandle.c:257
 handle_to_path fs/fhandle.c:385 [inline]
 do_handle_open+0x8cc/0xb8c fs/fhandle.c:403
 __do_sys_open_by_handle_at fs/fhandle.c:443 [inline]
 __se_sys_open_by_handle_at fs/fhandle.c:434 [inline]
 __arm64_sys_open_by_handle_at+0x80/0x94 fs/fhandle.c:434
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

Allocated by task 6466:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x40/0x78 mm/kasan/common.c:68
 kasan_save_alloc_info+0x40/0x50 mm/kasan/generic.c:562
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0xac/0xc4 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4294 [inline]
 __kmalloc_noprof+0x32c/0x54c mm/slub.c:4306
 kmalloc_noprof include/linux/slab.h:905 [inline]
 handle_to_path fs/fhandle.c:357 [inline]
 do_handle_open+0x5a4/0xb8c fs/fhandle.c:403
 __do_sys_open_by_handle_at fs/fhandle.c:443 [inline]
 __se_sys_open_by_handle_at fs/fhandle.c:434 [inline]
 __arm64_sys_open_by_handle_at+0x80/0x94 fs/fhandle.c:434
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

The buggy address belongs to the object at ffff0000cc030d80
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes to the right of
 allocated 20-byte region [ffff0000cc030d80, ffff0000cc030d94)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10c030
anon flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 05ffc00000000000 ffff0000c0001780 0000000000000000 dead000000000001
raw: 0000000000000000 0000000080400040 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000cc030c80: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
 ffff0000cc030d00: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
>ffff0000cc030d80: 00 00 04 fc fc fc fc fc fa fb fb fb fc fc fc fc
                         ^
 ffff0000cc030e00: 00 00 00 fc fc fc fc fc fa fb fb fb fc fc fc fc
 ffff0000cc030e80: 00 00 00 fc fc fc fc fc 00 00 00 fc fc fc fc fc
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
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If the report is a duplicate of another one, reply with:
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#syz undup

Re: [syzbot] [isofs?] KASAN: slab-out-of-bounds Read in isofs_fh_to_parent

[Edward Adam Davis]

#syz test

diff --git a/fs/fhandle.c b/fs/fhandle.c
index 3e092ae6d142..a31c0291a473 100644
--- a/fs/fhandle.c
+++ b/fs/fhandle.c
@@ -344,7 +344,7 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
 		goto out_path;
 	}
 	if ((f_handle.handle_bytes > MAX_HANDLE_SZ) ||
-	    (f_handle.handle_bytes == 0)) {
+	    (f_handle.handle_bytes < 16)) {
 		retval = -EINVAL;
 		goto out_path;
 	}

Re: [syzbot] [isofs?] KASAN: slab-out-of-bounds Read in isofs_fh_to_parent

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+4d7cd7dd0ce1aa8d5c65@syzkaller.appspotmail.com
Tested-by: syzbot+4d7cd7dd0ce1aa8d5c65@syzkaller.appspotmail.com

Tested on:

commit:         d6b13dbd Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=148de178580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=114db1c77c985e53
dashboard link: https://syzkaller.appspot.com/bug?extid=4d7cd7dd0ce1aa8d5c65
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=120a2fb0580000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [isofs?] KASAN: slab-out-of-bounds Read in isofs_fh_to_parent

[Edward Adam Davis]

#syz test

diff --git a/fs/isofs/export.c b/fs/isofs/export.c
index 35768a63fb1d..421d247fae52 100644
--- a/fs/isofs/export.c
+++ b/fs/isofs/export.c
@@ -180,7 +180,7 @@ static struct dentry *isofs_fh_to_parent(struct super_block *sb,
 		return NULL;
 
 	return isofs_export_iget(sb,
-			fh_len > 2 ? ifid->parent_block : 0,
+			fh_len > 3 ? ifid->parent_block : 0,
 			ifid->parent_offset,
 			fh_len > 4 ? ifid->parent_generation : 0);
 }

Re: [syzbot] [isofs?] KASAN: slab-out-of-bounds Read in isofs_fh_to_parent

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+4d7cd7dd0ce1aa8d5c65@syzkaller.appspotmail.com
Tested-by: syzbot+4d7cd7dd0ce1aa8d5c65@syzkaller.appspotmail.com

Tested on:

commit:         d6b13dbd Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=11d92a74580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=114db1c77c985e53
dashboard link: https://syzkaller.appspot.com/bug?extid=4d7cd7dd0ce1aa8d5c65
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1479023f980000

Note: testing is done by a robot and is best-effort only.

[PATCH] isofs: Prevent the use of too small fid

[Edward Adam Davis]

syzbot reported a slab-out-of-bounds Read in isofs_fh_to_parent. [1]

The handle_bytes value passed in by the reproducing program is equal to 12.
In handle_to_path(), only 12 bytes of memory are allocated for the structure
file_handle->f_handle member, which causes an out-of-bounds access when
accessing the member parent_block of the structure isofs_fid in isofs,
because accessing parent_block requires at least 16 bytes of f_handle.
Here, fh_len is used to indirectly confirm that the value of handle_bytes
is greater than 3 before accessing parent_block.

[1]
BUG: KASAN: slab-out-of-bounds in isofs_fh_to_parent+0x1b8/0x210 fs/isofs/export.c:183
Read of size 4 at addr ffff0000cc030d94 by task syz-executor215/6466
CPU: 1 UID: 0 PID: 6466 Comm: syz-executor215 Not tainted 6.14.0-rc7-syzkaller-ga2392f333575 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0x198/0x550 mm/kasan/report.c:521
 kasan_report+0xd8/0x138 mm/kasan/report.c:634
 __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
 isofs_fh_to_parent+0x1b8/0x210 fs/isofs/export.c:183
 exportfs_decode_fh_raw+0x2dc/0x608 fs/exportfs/expfs.c:523
 do_handle_to_path+0xa0/0x198 fs/fhandle.c:257
 handle_to_path fs/fhandle.c:385 [inline]
 do_handle_open+0x8cc/0xb8c fs/fhandle.c:403
 __do_sys_open_by_handle_at fs/fhandle.c:443 [inline]
 __se_sys_open_by_handle_at fs/fhandle.c:434 [inline]
 __arm64_sys_open_by_handle_at+0x80/0x94 fs/fhandle.c:434
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

Allocated by task 6466:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x40/0x78 mm/kasan/common.c:68
 kasan_save_alloc_info+0x40/0x50 mm/kasan/generic.c:562
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0xac/0xc4 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4294 [inline]
 __kmalloc_noprof+0x32c/0x54c mm/slub.c:4306
 kmalloc_noprof include/linux/slab.h:905 [inline]
 handle_to_path fs/fhandle.c:357 [inline]
 do_handle_open+0x5a4/0xb8c fs/fhandle.c:403
 __do_sys_open_by_handle_at fs/fhandle.c:443 [inline]
 __se_sys_open_by_handle_at fs/fhandle.c:434 [inline]
 __arm64_sys_open_by_handle_at+0x80/0x94 fs/fhandle.c:434
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

Reported-by: syzbot+4d7cd7dd0ce1aa8d5c65@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=4d7cd7dd0ce1aa8d5c65
Tested-by: syzbot+4d7cd7dd0ce1aa8d5c65@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 fs/isofs/export.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/isofs/export.c b/fs/isofs/export.c
index 35768a63fb1d..421d247fae52 100644
--- a/fs/isofs/export.c
+++ b/fs/isofs/export.c
@@ -180,7 +180,7 @@ static struct dentry *isofs_fh_to_parent(struct super_block *sb,
 		return NULL;
 
 	return isofs_export_iget(sb,
-			fh_len > 2 ? ifid->parent_block : 0,
+			fh_len > 3 ? ifid->parent_block : 0,
 			ifid->parent_offset,
 			fh_len > 4 ? ifid->parent_generation : 0);
 }
-- 
2.43.0

Re: [PATCH] isofs: Prevent the use of too small fid

[Jan Kara]

On Fri 04-04-25 13:31:29, Edward Adam Davis wrote:
> syzbot reported a slab-out-of-bounds Read in isofs_fh_to_parent. [1]
> 
> The handle_bytes value passed in by the reproducing program is equal to 12.
> In handle_to_path(), only 12 bytes of memory are allocated for the structure
> file_handle->f_handle member, which causes an out-of-bounds access when
> accessing the member parent_block of the structure isofs_fid in isofs,
> because accessing parent_block requires at least 16 bytes of f_handle.
> Here, fh_len is used to indirectly confirm that the value of handle_bytes
> is greater than 3 before accessing parent_block.
> 
> [1]
> BUG: KASAN: slab-out-of-bounds in isofs_fh_to_parent+0x1b8/0x210 fs/isofs/export.c:183
> Read of size 4 at addr ffff0000cc030d94 by task syz-executor215/6466
> CPU: 1 UID: 0 PID: 6466 Comm: syz-executor215 Not tainted 6.14.0-rc7-syzkaller-ga2392f333575 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
> Call trace:
>  show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C)
>  __dump_stack lib/dump_stack.c:94 [inline]
>  dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
>  print_address_description mm/kasan/report.c:408 [inline]
>  print_report+0x198/0x550 mm/kasan/report.c:521
>  kasan_report+0xd8/0x138 mm/kasan/report.c:634
>  __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
>  isofs_fh_to_parent+0x1b8/0x210 fs/isofs/export.c:183
>  exportfs_decode_fh_raw+0x2dc/0x608 fs/exportfs/expfs.c:523
>  do_handle_to_path+0xa0/0x198 fs/fhandle.c:257
>  handle_to_path fs/fhandle.c:385 [inline]
>  do_handle_open+0x8cc/0xb8c fs/fhandle.c:403
>  __do_sys_open_by_handle_at fs/fhandle.c:443 [inline]
>  __se_sys_open_by_handle_at fs/fhandle.c:434 [inline]
>  __arm64_sys_open_by_handle_at+0x80/0x94 fs/fhandle.c:434
>  __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
>  invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
>  el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
>  do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
>  el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
>  el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
>  el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
> 
> Allocated by task 6466:
>  kasan_save_stack mm/kasan/common.c:47 [inline]
>  kasan_save_track+0x40/0x78 mm/kasan/common.c:68
>  kasan_save_alloc_info+0x40/0x50 mm/kasan/generic.c:562
>  poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
>  __kasan_kmalloc+0xac/0xc4 mm/kasan/common.c:394
>  kasan_kmalloc include/linux/kasan.h:260 [inline]
>  __do_kmalloc_node mm/slub.c:4294 [inline]
>  __kmalloc_noprof+0x32c/0x54c mm/slub.c:4306
>  kmalloc_noprof include/linux/slab.h:905 [inline]
>  handle_to_path fs/fhandle.c:357 [inline]
>  do_handle_open+0x5a4/0xb8c fs/fhandle.c:403
>  __do_sys_open_by_handle_at fs/fhandle.c:443 [inline]
>  __se_sys_open_by_handle_at fs/fhandle.c:434 [inline]
>  __arm64_sys_open_by_handle_at+0x80/0x94 fs/fhandle.c:434
>  __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
>  invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
>  el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
>  do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
>  el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
>  el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
>  el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
> 
> Reported-by: syzbot+4d7cd7dd0ce1aa8d5c65@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=4d7cd7dd0ce1aa8d5c65
> Tested-by: syzbot+4d7cd7dd0ce1aa8d5c65@syzkaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>

Thanks! This is indeed an old bug :). Added to my tree.

								Honza

> ---
>  fs/isofs/export.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/isofs/export.c b/fs/isofs/export.c
> index 35768a63fb1d..421d247fae52 100644
> --- a/fs/isofs/export.c
> +++ b/fs/isofs/export.c
> @@ -180,7 +180,7 @@ static struct dentry *isofs_fh_to_parent(struct super_block *sb,
>  		return NULL;
>  
>  	return isofs_export_iget(sb,
> -			fh_len > 2 ? ifid->parent_block : 0,
> +			fh_len > 3 ? ifid->parent_block : 0,
>  			ifid->parent_offset,
>  			fh_len > 4 ? ifid->parent_generation : 0);
>  }
> -- 
> 2.43.0
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR