linux-kernel - [syzbot] KMSAN: uninit-value in p9pdu

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Message-ID: <000000000000f1e24805d4fd6d50@google.com>
Date:   Fri, 07 Jan 2022 04:50:19 -0800
From:   syzbot <syzbot+99f920ef970b8c366bfe@...kaller.appspotmail.com>
To:     asmadeus@...ewreck.org, davem@...emloft.net, ericvh@...il.com,
        glider@...gle.com, kuba@...nel.org, linux-kernel@...r.kernel.org,
        lucho@...kov.net, netdev@...r.kernel.org,
        syzkaller-bugs@...glegroups.com,
        v9fs-developer@...ts.sourceforge.net
Subject: [syzbot] KMSAN: uninit-value in p9pdu_vwritef

Hello,

syzbot found the following issue on:

HEAD commit:    81c325bbf94e kmsan: hooks: do not check memory in kmsan_in..
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=10501807b00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2d8b9a11641dc9aa
dashboard link: https://syzkaller.appspot.com/bug?extid=99f920ef970b8c366bfe
compiler:       clang version 14.0.0 (/usr/local/google/src/llvm-git-monorepo 2b554920f11c8b763cd9ed9003f4e19b919b8e1f), GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+99f920ef970b8c366bfe@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in check_copy_size include/linux/thread_info.h:216 [inline]
BUG: KMSAN: uninit-value in copy_from_iter include/linux/uio.h:161 [inline]
BUG: KMSAN: uninit-value in copy_from_iter_full include/linux/uio.h:170 [inline]
BUG: KMSAN: uninit-value in pdu_write_u net/9p/protocol.c:68 [inline]
BUG: KMSAN: uninit-value in p9pdu_vwritef+0x458f/0x5100 net/9p/protocol.c:439
 check_copy_size include/linux/thread_info.h:216 [inline]
 copy_from_iter include/linux/uio.h:161 [inline]
 copy_from_iter_full include/linux/uio.h:170 [inline]
 pdu_write_u net/9p/protocol.c:68 [inline]
 p9pdu_vwritef+0x458f/0x5100 net/9p/protocol.c:439
 p9_client_prepare_req+0xe64/0x16d0 net/9p/client.c:703
 p9_client_rpc+0x28b/0x1460 net/9p/client.c:734
 p9_client_write+0x722/0xfa0 net/9p/client.c:1662
 v9fs_fid_xattr_set+0x3a6/0x520 fs/9p/xattr.c:130
 v9fs_xattr_set fs/9p/xattr.c:100 [inline]
 v9fs_xattr_handler_set+0x1b4/0x220 fs/9p/xattr.c:159
 __vfs_setxattr+0x910/0x960 fs/xattr.c:180
 __vfs_setxattr_noperm+0x382/0xe80 fs/xattr.c:214
 __vfs_setxattr_locked+0x629/0x690 fs/xattr.c:275
 vfs_setxattr+0x440/0x7b0 fs/xattr.c:301
 setxattr+0x42e/0x7c0 fs/xattr.c:575
 path_setxattr+0x2f4/0x520 fs/xattr.c:595
 __do_sys_setxattr fs/xattr.c:611 [inline]
 __se_sys_setxattr fs/xattr.c:607 [inline]
 __ia32_sys_setxattr+0x15b/0x1c0 fs/xattr.c:607
 do_syscall_32_irqs_on arch/x86/entry/common.c:114 [inline]
 __do_fast_syscall_32+0x96/0xf0 arch/x86/entry/common.c:180
 do_fast_syscall_32+0x34/0x70 arch/x86/entry/common.c:205
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:248
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

Uninit was created at:
 slab_post_alloc_hook mm/slab.h:524 [inline]
 slab_alloc_node mm/slub.c:3251 [inline]
 slab_alloc mm/slub.c:3259 [inline]
 kmem_cache_alloc_trace+0xaca/0x1140 mm/slub.c:3276
 kmalloc include/linux/slab.h:590 [inline]
 p9_fid_create+0x7d/0x470 net/9p/client.c:892
 p9_client_walk+0x15f/0xe50 net/9p/client.c:1175
 clone_fid fs/9p/fid.h:21 [inline]
 v9fs_fid_xattr_set+0x244/0x520 fs/9p/xattr.c:118
 v9fs_xattr_set fs/9p/xattr.c:100 [inline]
 v9fs_xattr_handler_set+0x1b4/0x220 fs/9p/xattr.c:159
 __vfs_setxattr+0x910/0x960 fs/xattr.c:180
 __vfs_setxattr_noperm+0x382/0xe80 fs/xattr.c:214
 __vfs_setxattr_locked+0x629/0x690 fs/xattr.c:275
 vfs_setxattr+0x440/0x7b0 fs/xattr.c:301
 setxattr+0x42e/0x7c0 fs/xattr.c:575
 path_setxattr+0x2f4/0x520 fs/xattr.c:595
 __do_sys_setxattr fs/xattr.c:611 [inline]
 __se_sys_setxattr fs/xattr.c:607 [inline]
 __ia32_sys_setxattr+0x15b/0x1c0 fs/xattr.c:607
 do_syscall_32_irqs_on arch/x86/entry/common.c:114 [inline]
 __do_fast_syscall_32+0x96/0xf0 arch/x86/entry/common.c:180
 do_fast_syscall_32+0x34/0x70 arch/x86/entry/common.c:205
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:248
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

CPU: 0 PID: 22907 Comm: syz-executor.4 Tainted: G S                5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
=====================================================


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