Re: [syzbot] [netfs?] KASAN: slab-use-after-free Read in iov_iter_advance

[syzbot <syzbot+7c48153a9d788824044b@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in p9_client_create

------------[ cut here ]------------
kmem_cache of name 'syzkaller' already exists
WARNING: CPU: 1 PID: 7290 at mm/slab_common.c:107 kmem_cache_sanity_check mm/slab_common.c:107 [inline]
WARNING: CPU: 1 PID: 7290 at mm/slab_common.c:107 __kmem_cache_create_args+0xb0/0x3c0 mm/slab_common.c:294
Modules linked in:
CPU: 1 UID: 0 PID: 7290 Comm: syz-executor302 Not tainted 6.11.0-syzkaller-07341-gbaeb9a7d8b60-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
RIP: 0010:kmem_cache_sanity_check mm/slab_common.c:107 [inline]
RIP: 0010:__kmem_cache_create_args+0xb0/0x3c0 mm/slab_common.c:294
Code: 98 48 3d d0 de 11 8e 74 25 48 8b 7b 60 48 89 ee e8 35 ae 3c 09 85 c0 75 e0 90 48 c7 c7 18 bb 59 8d 48 89 ee e8 01 38 80 ff 90 <0f> 0b 90 90 be 20 00 00 00 48 89 ef e8 bf af 3c 09 48 85 c0 0f 85
RSP: 0018:ffffc90002fef8f0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff8880289cec80 RCX: ffffffff814e16a9
RDX: ffff88806be39e00 RSI: ffffffff814e16b6 RDI: 0000000000000001
RBP: ffffffff9023f4c1 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000008004 R14: ffffc90002fef9f0 R15: 0000000000020018
FS:  000055558975d380(0000) GS:ffff8880b8900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f479381ae40 CR3: 00000000794e6000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 kmem_cache_create_usercopy include/linux/slab.h:361 [inline]
 p9_client_create+0xec8/0x11c0 net/9p/client.c:1042
 v9fs_session_init+0x1f8/0x1a80 fs/9p/v9fs.c:410
 v9fs_mount+0xc6/0xa50 fs/9p/vfs_super.c:122
 legacy_get_tree+0x10c/0x220 fs/fs_context.c:662
 vfs_get_tree+0x92/0x380 fs/super.c:1800
 do_new_mount fs/namespace.c:3507 [inline]
 path_mount+0x14e6/0x1f20 fs/namespace.c:3834
 do_mount fs/namespace.c:3847 [inline]
 __do_sys_mount fs/namespace.c:4055 [inline]
 __se_sys_mount fs/namespace.c:4032 [inline]
 __x64_sys_mount+0x294/0x320 fs/namespace.c:4032
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f47937e7f39
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 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:00007ffdc8834e28 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f47937e7f39
RDX: 0000000020000040 RSI: 0000000020000000 RDI: 0000000000000000
RBP: 00007f479383104e R08: 0000000020000300 R09: 0000000000000006
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdc8834e3c
R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001
 </TASK>


Tested on:

commit:         baeb9a7d Merge tag 'sched-rt-2024-09-17' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14a8ff00580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5a0a1caedf9d578f
dashboard link: https://syzkaller.appspot.com/bug?extid=7c48153a9d788824044b
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=16402ca9980000