[syzbot] [net?] [afs?] WARNING in rxrpc_alloc_data_txbuf

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 75c2946db360 Merge tag 'wireless-next-2024-03-08' of git:/..
git tree: net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=16700bf2180000
kernel config: https://syzkaller.appspot.com/x/.config?x=bc4c0052bd7e51d8
dashboard link: https://syzkaller.appspot.com/bug?extid=150fa730f40bce72aa05
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=163dfe92180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17818449180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b9317816c71d/disk-75c2946d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0d18e4d62eff/vmlinux-75c2946d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9089b556e6fd/bzImage-75c2946d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+150fa7...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 5074 at include/linux/gfp.h:323 page_frag_alloc_align include/linux/gfp.h:323 [inline]
WARNING: CPU: 1 PID: 5074 at include/linux/gfp.h:323 rxrpc_alloc_data_txbuf+0x7cf/0xda0 net/rxrpc/txbuf.c:36
Modules linked in:
CPU: 1 PID: 5074 Comm: syz-executor206 Not tainted 6.8.0-rc7-syzkaller-02348-g75c2946db360 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
RIP: 0010:page_frag_alloc_align include/linux/gfp.h:323 [inline]
RIP: 0010:rxrpc_alloc_data_txbuf+0x7cf/0xda0 net/rxrpc/txbuf.c:36
Code: 96 01 f7 4c 89 f7 e8 a0 f1 58 f7 45 31 f6 4c 89 f0 48 83 c4 40 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc e8 42 96 01 f7 90 <0f> 0b 90 e9 8d f9 ff ff 44 89 fe 83 e6 01 31 ff e8 6c 9a 01 f7 44
RSP: 0018:ffffc9000398f328 EFLAGS: 00010293
RAX: ffffffff8a91d8de RBX: 0000000000000000 RCX: ffff8880284f5940
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffffffff8a91d266 R09: 1ffffffff1f0c0fd
R10: dffffc0000000000 R11: fffffbfff1f0c0fe R12: ffff88802e3a4390
R13: ffff88801b6b5280 R14: ffff88801caf4900 R15: 0000000000000cc0
FS: 0000555556094380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020005c08 CR3: 00000000755e2000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
rxrpc_send_data+0xb17/0x2800 net/rxrpc/sendmsg.c:351
rxrpc_do_sendmsg+0x1569/0x1910 net/rxrpc/sendmsg.c:718
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0x221/0x270 net/socket.c:745
____sys_sendmsg+0x525/0x7d0 net/socket.c:2584
___sys_sendmsg net/socket.c:2638 [inline]
__sys_sendmmsg+0x3b2/0x740 net/socket.c:2724
__do_sys_sendmmsg net/socket.c:2753 [inline]
__se_sys_sendmmsg net/socket.c:2750 [inline]
__x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2750
do_syscall_64+0xf9/0x240
entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7fb02c0cf369
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 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:00007ffdc045a3f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007ffdc045a5c8 RCX: 00007fb02c0cf369
RDX: 0000000000000001 RSI: 0000000020005c00 RDI: 0000000000000003
RBP: 00007fb02c142610 R08: 00007ffdc045a5c8 R09: 00007ffdc045a5c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffdc045a5b8 R14: 0000000000000001 R15: 0000000000000001
</TASK>


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[David Howells]

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git rxrpc-iothread-20240312

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+150fa7...@syzkaller.appspotmail.com

Tested on:

commit: d1f2f222 rxrpc: Fix error check on ->alloc_txbuf()
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git rxrpc-iothread-20240312
console output: https://syzkaller.appspot.com/x/log.txt?x=13a2f71e180000
kernel config: https://syzkaller.appspot.com/x/.config?x=63afafeedf00ef8f

dashboard link: https://syzkaller.appspot.com/bug?extid=150fa730f40bce72aa05
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.