[syzbot] [selinux?] WARNING in hashtab_init

[syzbot] [selinux?] WARNING in hashtab_init

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    52da431bf03b Merge tag 'libnvdimm-fixes-6.16-rc3' of git:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=144635d4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4130f4d8a06c3e71
dashboard link: https://syzkaller.appspot.com/bug?extid=bc2c99c2929c3d219fb3
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12a1f50c580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1094050c580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-52da431b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0ebc79a3dea1/vmlinux-52da431b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2b1157e117a2/bzImage-52da431b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bc2c99c2929c3d219fb3@syzkaller.appspotmail.com

WARNING: CPU: 3 PID: 5931 at mm/page_alloc.c:4935 __alloc_frozen_pages_noprof+0x30b/0x23f0 mm/page_alloc.c:4935
Modules linked in:
CPU: 3 UID: 0 PID: 5931 Comm: syz-executor128 Not tainted 6.16.0-rc2-syzkaller-00047-g52da431bf03b #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:__alloc_frozen_pages_noprof+0x30b/0x23f0 mm/page_alloc.c:4935
Code: f0 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 83 fe 0a 0f 86 0a fe ff ff 80 3d 83 6e 7a 0e 00 75 0b c6 05 7a 6e 7a 0e 01 90 <0f> 0b 90 45 31 f6 eb 81 4d 85 f6 74 22 44 89 fa 89 ee 4c 89 f7 e8
RSP: 0018:ffffc90003d87438 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000015 RDI: 0000000000040dc0
RBP: 0000000200000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000040000000 R11: 0000000000000001 R12: 0000000000000015
R13: 1ffff920007b0e9c R14: 0000000200000000 R15: 0000000000000015
FS:  0000555574b0f380(0000) GS:ffff8880d6a53000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 000000002a80f000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __alloc_pages_noprof+0xb/0x1b0 mm/page_alloc.c:4993
 __alloc_pages_node_noprof include/linux/gfp.h:284 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:311 [inline]
 ___kmalloc_large_node+0x84/0x1e0 mm/slub.c:4272
 __kmalloc_large_node_noprof+0x1c/0x70 mm/slub.c:4300
 __do_kmalloc_node mm/slub.c:4316 [inline]
 __kmalloc_noprof.cold+0xc/0x61 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kmalloc_array_noprof include/linux/slab.h:948 [inline]
 hashtab_init+0x1b1/0x290 security/selinux/ss/hashtab.c:43
 common_read+0x1c2/0x3d0 security/selinux/ss/policydb.c:1172
 policydb_read+0x874/0x3220 security/selinux/ss/policydb.c:2578
 security_load_policy+0x15c/0x12c0 security/selinux/ss/services.c:2299
 sel_write_load+0x332/0x1bd0 security/selinux/selinuxfs.c:603
 vfs_write+0x2a0/0x1150 fs/read_write.c:684
 ksys_write+0x12a/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0fd65a5d79
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc49f31638 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000200000000300 RCX: 00007f0fd65a5d79
RDX: 0000000000002000 RSI: 0000200000000000 RDI: 0000000000000003
RBP: 0000200000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000008f R11: 0000000000000246 R12: 00007f0fd65f419c
R13: 00007f0fd65ef082 R14: 0000000000000001 R15: 0000000000000001
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

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:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

Re: [syzbot] [selinux?] WARNING in hashtab_init

[Paul Moore]

On Wed, Jun 18, 2025 at 9:07 AM syzbot
<syzbot+bc2c99c2929c3d219fb3@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    52da431bf03b Merge tag 'libnvdimm-fixes-6.16-rc3' of git:/..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=144635d4580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=4130f4d8a06c3e71
> dashboard link: https://syzkaller.appspot.com/bug?extid=bc2c99c2929c3d219fb3
> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12a1f50c580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1094050c580000
>
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-52da431b.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/0ebc79a3dea1/vmlinux-52da431b.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/2b1157e117a2/bzImage-52da431b.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+bc2c99c2929c3d219fb3@syzkaller.appspotmail.com
>
> WARNING: CPU: 3 PID: 5931 at mm/page_alloc.c:4935 __alloc_frozen_pages_noprof+0x30b/0x23f0 mm/page_alloc.c:4935
> Modules linked in:
> CPU: 3 UID: 0 PID: 5931 Comm: syz-executor128 Not tainted 6.16.0-rc2-syzkaller-00047-g52da431bf03b #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> RIP: 0010:__alloc_frozen_pages_noprof+0x30b/0x23f0 mm/page_alloc.c:4935
> Code: f0 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 83 fe 0a 0f 86 0a fe ff ff 80 3d 83 6e 7a 0e 00 75 0b c6 05 7a 6e 7a 0e 01 90 <0f> 0b 90 45 31 f6 eb 81 4d 85 f6 74 22 44 89 fa 89 ee 4c 89 f7 e8
> RSP: 0018:ffffc90003d87438 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: 0000000000000015 RDI: 0000000000040dc0
> RBP: 0000000200000000 R08: 0000000000000005 R09: 0000000000000000
> R10: 0000000040000000 R11: 0000000000000001 R12: 0000000000000015
> R13: 1ffff920007b0e9c R14: 0000000200000000 R15: 0000000000000015
> FS:  0000555574b0f380(0000) GS:ffff8880d6a53000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000200000001000 CR3: 000000002a80f000 CR4: 0000000000352ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  __alloc_pages_noprof+0xb/0x1b0 mm/page_alloc.c:4993

Looks like another case where we should probably add GFP_NOWARN.

>  __alloc_pages_node_noprof include/linux/gfp.h:284 [inline]
>  alloc_pages_node_noprof include/linux/gfp.h:311 [inline]
>  ___kmalloc_large_node+0x84/0x1e0 mm/slub.c:4272
>  __kmalloc_large_node_noprof+0x1c/0x70 mm/slub.c:4300
>  __do_kmalloc_node mm/slub.c:4316 [inline]
>  __kmalloc_noprof.cold+0xc/0x61 mm/slub.c:4340
>  kmalloc_noprof include/linux/slab.h:909 [inline]
>  kmalloc_array_noprof include/linux/slab.h:948 [inline]
>  hashtab_init+0x1b1/0x290 security/selinux/ss/hashtab.c:43

This would be the right spot, in the kcalloc() call.  I'll throw
together a quick patch in a little bit.

>  common_read+0x1c2/0x3d0 security/selinux/ss/policydb.c:1172
>  policydb_read+0x874/0x3220 security/selinux/ss/policydb.c:2578
>  security_load_policy+0x15c/0x12c0 security/selinux/ss/services.c:2299
>  sel_write_load+0x332/0x1bd0 security/selinux/selinuxfs.c:603
>  vfs_write+0x2a0/0x1150 fs/read_write.c:684
>  ksys_write+0x12a/0x250 fs/read_write.c:738
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f0fd65a5d79
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffc49f31638 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 0000200000000300 RCX: 00007f0fd65a5d79
> RDX: 0000000000002000 RSI: 0000200000000000 RDI: 0000000000000003
> RBP: 0000200000000000 R08: 0000000000000000 R09: 0000000000000000
> R10: 000000000000008f R11: 0000000000000246 R12: 00007f0fd65f419c
> R13: 00007f0fd65ef082 R14: 0000000000000001 R15: 0000000000000001
>  </TASK>

-- 
paul-moore.com

Re: [syzbot] [selinux?] WARNING in hashtab_init

[Paul Moore]

[-- Attachment #1: Type: text/plain, Size: 5377 bytes --]

#syz test

On Wed, Jun 18, 2025 at 9:07 AM syzbot
<syzbot+bc2c99c2929c3d219fb3@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    52da431bf03b Merge tag 'libnvdimm-fixes-6.16-rc3' of git:/..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=144635d4580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=4130f4d8a06c3e71
> dashboard link: https://syzkaller.appspot.com/bug?extid=bc2c99c2929c3d219fb3
> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12a1f50c580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1094050c580000
>
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-52da431b.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/0ebc79a3dea1/vmlinux-52da431b.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/2b1157e117a2/bzImage-52da431b.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+bc2c99c2929c3d219fb3@syzkaller.appspotmail.com
>
> WARNING: CPU: 3 PID: 5931 at mm/page_alloc.c:4935 __alloc_frozen_pages_noprof+0x30b/0x23f0 mm/page_alloc.c:4935
> Modules linked in:
> CPU: 3 UID: 0 PID: 5931 Comm: syz-executor128 Not tainted 6.16.0-rc2-syzkaller-00047-g52da431bf03b #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> RIP: 0010:__alloc_frozen_pages_noprof+0x30b/0x23f0 mm/page_alloc.c:4935
> Code: f0 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 83 fe 0a 0f 86 0a fe ff ff 80 3d 83 6e 7a 0e 00 75 0b c6 05 7a 6e 7a 0e 01 90 <0f> 0b 90 45 31 f6 eb 81 4d 85 f6 74 22 44 89 fa 89 ee 4c 89 f7 e8
> RSP: 0018:ffffc90003d87438 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: 0000000000000015 RDI: 0000000000040dc0
> RBP: 0000000200000000 R08: 0000000000000005 R09: 0000000000000000
> R10: 0000000040000000 R11: 0000000000000001 R12: 0000000000000015
> R13: 1ffff920007b0e9c R14: 0000000200000000 R15: 0000000000000015
> FS:  0000555574b0f380(0000) GS:ffff8880d6a53000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000200000001000 CR3: 000000002a80f000 CR4: 0000000000352ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  __alloc_pages_noprof+0xb/0x1b0 mm/page_alloc.c:4993
>  __alloc_pages_node_noprof include/linux/gfp.h:284 [inline]
>  alloc_pages_node_noprof include/linux/gfp.h:311 [inline]
>  ___kmalloc_large_node+0x84/0x1e0 mm/slub.c:4272
>  __kmalloc_large_node_noprof+0x1c/0x70 mm/slub.c:4300
>  __do_kmalloc_node mm/slub.c:4316 [inline]
>  __kmalloc_noprof.cold+0xc/0x61 mm/slub.c:4340
>  kmalloc_noprof include/linux/slab.h:909 [inline]
>  kmalloc_array_noprof include/linux/slab.h:948 [inline]
>  hashtab_init+0x1b1/0x290 security/selinux/ss/hashtab.c:43
>  common_read+0x1c2/0x3d0 security/selinux/ss/policydb.c:1172
>  policydb_read+0x874/0x3220 security/selinux/ss/policydb.c:2578
>  security_load_policy+0x15c/0x12c0 security/selinux/ss/services.c:2299
>  sel_write_load+0x332/0x1bd0 security/selinux/selinuxfs.c:603
>  vfs_write+0x2a0/0x1150 fs/read_write.c:684
>  ksys_write+0x12a/0x250 fs/read_write.c:738
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f0fd65a5d79
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffc49f31638 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 0000200000000300 RCX: 00007f0fd65a5d79
> RDX: 0000000000002000 RSI: 0000200000000000 RDI: 0000000000000003
> RBP: 0000200000000000 R08: 0000000000000000 R09: 0000000000000000
> R10: 000000000000008f R11: 0000000000000246 R12: 00007f0fd65f419c
> R13: 00007f0fd65ef082 R14: 0000000000000001 R15: 0000000000000001
>  </TASK>
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> 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:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup

-- 
paul-moore.com

[-- Attachment #2: 01-selinux-hashtab_gfpnowarn.patch --]
[-- Type: text/x-patch, Size: 1199 bytes --]

selinux: add __GFP_NOWARN to hashtab_init() allocations

From: Paul Moore <paul@paul-moore.com>

As reported by syzbot, hashtab_init() can be affected by abnormally
large policy loads which would cause the kernel's allocator to emit
a warning in some configurations.  Since the SELinux hashtab_init()
code handles the case where the allocation fails, due to a large
request or some other reason, we can safely add the __GFP_NOWARN flag
to squelch these abnormally large allocation warnings.

Reported-by: syzbot+bc2c99c2929c3d219fb3@syzkaller.appspotmail.com
Signed-off-by: Paul Moore <paul@paul-moore.com>
---
 security/selinux/ss/hashtab.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/security/selinux/ss/hashtab.c b/security/selinux/ss/hashtab.c
index 383fd2d70878..1382eb3bfde1 100644
--- a/security/selinux/ss/hashtab.c
+++ b/security/selinux/ss/hashtab.c
@@ -40,7 +40,8 @@ int hashtab_init(struct hashtab *h, u32 nel_hint)
 	h->htable = NULL;
 
 	if (size) {
-		h->htable = kcalloc(size, sizeof(*h->htable), GFP_KERNEL);
+		h->htable = kcalloc(size, sizeof(*h->htable),
+				    GFP_KERNEL | __GFP_NOWARN);
 		if (!h->htable)
 			return -ENOMEM;
 		h->size = size;

Re: [syzbot] [selinux?] WARNING in hashtab_init

[syzbot]

Hello,

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

Reported-by: syzbot+bc2c99c2929c3d219fb3@syzkaller.appspotmail.com
Tested-by: syzbot+bc2c99c2929c3d219fb3@syzkaller.appspotmail.com

Tested on:

commit:         52da431b Merge tag 'libnvdimm-fixes-6.16-rc3' of git:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1206050c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4130f4d8a06c3e71
dashboard link: https://syzkaller.appspot.com/bug?extid=bc2c99c2929c3d219fb3
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=12163e82580000

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