[syzbot] [net?] KMSAN: uninit-value in hsr_get_node (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0bbac3facb5d Linux 6.9-rc4
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=15d9a36d180000
kernel config: https://syzkaller.appspot.com/x/.config?x=87a805e655619c64
dashboard link: https://syzkaller.appspot.com/bug?extid=a81f2759d022496b40ab
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=14069fcb180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=155da7cb180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/93eb2bab28b5/disk-0bbac3fa.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/47a883d2dfaa/vmlinux-0bbac3fa.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6bc56900ec1d/bzImage-0bbac3fa.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a81f27...@syzkaller.appspotmail.com

syz_tun: entered promiscuous mode
batadv_slave_0: entered promiscuous mode
=====================================================
BUG: KMSAN: uninit-value in hsr_get_node+0xab0/0xad0 net/hsr/hsr_framereg.c:250
hsr_get_node+0xab0/0xad0 net/hsr/hsr_framereg.c:250
fill_frame_info net/hsr/hsr_forward.c:577 [inline]
hsr_forward_skb+0x330/0x30e0 net/hsr/hsr_forward.c:615
hsr_handle_frame+0xa20/0xb50 net/hsr/hsr_slave.c:69
__netif_receive_skb_core+0x1cff/0x6190 net/core/dev.c:5432
__netif_receive_skb_one_core net/core/dev.c:5536 [inline]
__netif_receive_skb+0xca/0xa00 net/core/dev.c:5652
netif_receive_skb_internal net/core/dev.c:5738 [inline]
netif_receive_skb+0x58/0x660 net/core/dev.c:5798
tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1549
tun_get_user+0x5566/0x69e0 drivers/net/tun.c:2002
tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048
call_write_iter include/linux/fs.h:2110 [inline]
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0xb63/0x1520 fs/read_write.c:590
ksys_write+0x20f/0x4c0 fs/read_write.c:643
__do_sys_write fs/read_write.c:655 [inline]
__se_sys_write fs/read_write.c:652 [inline]
__x64_sys_write+0x93/0xe0 fs/read_write.c:652
x64_sys_call+0x3062/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
__alloc_pages+0x9d6/0xe70 mm/page_alloc.c:4598
alloc_pages_mpol+0x299/0x990 mm/mempolicy.c:2264
alloc_pages+0x1bf/0x1e0 mm/mempolicy.c:2335
skb_page_frag_refill+0x2bf/0x7c0 net/core/sock.c:2921
tun_build_skb drivers/net/tun.c:1679 [inline]
tun_get_user+0x1258/0x69e0 drivers/net/tun.c:1819
tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048
call_write_iter include/linux/fs.h:2110 [inline]
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0xb63/0x1520 fs/read_write.c:590
ksys_write+0x20f/0x4c0 fs/read_write.c:643
__do_sys_write fs/read_write.c:655 [inline]
__se_sys_write fs/read_write.c:652 [inline]
__x64_sys_write+0x93/0xe0 fs/read_write.c:652
x64_sys_call+0x3062/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 PID: 5050 Comm: syz-executor387 Not tainted 6.9.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
=====================================================


---
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[Jeongjun Park]

please test uninit-value in hsr_get_node

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KMSAN: uninit-value in hsr_get_node

CPU: 0 PID: 5497 Comm: syz-executor.0 Not tainted 6.9.0-rc4-syzkaller-00038-g8cd26fd90c1a #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
=====================================================

Tested on:

commit: 8cd26fd9 Merge tag 'for-6.9-rc4-tag' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1398c9ab180000

kernel config: https://syzkaller.appspot.com/x/.config?x=87a805e655619c64
dashboard link: https://syzkaller.appspot.com/bug?extid=a81f2759d022496b40ab
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.

[Jeongjun Park]

please test uninit-value in hsr_get_node

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

---
net/core/sock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 0963689a5950..847233e8f3e6 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2920,7 +2920,7 @@ bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t gfp)
/* Avoid direct reclaim but allow kswapd to wake */
pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) |
__GFP_COMP | __GFP_NOWARN |
- __GFP_NORETRY,
+ __GFP_NORETRY | __GFP_ZERO,
SKB_FRAG_PAGE_ORDER);
if (likely(pfrag->page)) {
pfrag->size = PAGE_SIZE << SKB_FRAG_PAGE_ORDER;
--
2.34.1

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+a81f27...@syzkaller.appspotmail.com

Tested on:

commit: 2668e3ae Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1405f520980000

kernel config: https://syzkaller.appspot.com/x/.config?x=87a805e655619c64
dashboard link: https://syzkaller.appspot.com/bug?extid=a81f2759d022496b40ab
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=1341bcfd180000

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

[Jeongjun Park]

please test uninit-value in hsr_get_node

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

---

drivers/net/tun.c | 2 +-

1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 0b3f21cba552..5300bbbc617d 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1676,7 +1676,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
rcu_read_unlock();

alloc_frag->offset = ALIGN((u64)alloc_frag->offset, SMP_CACHE_BYTES);
- if (unlikely(!skb_page_frag_refill(buflen, alloc_frag, GFP_KERNEL)))
+ if (unlikely(!skb_page_frag_refill(buflen, alloc_frag, GFP_KERNEL | __GFP_ZERO)))
return ERR_PTR(-ENOMEM);

buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
--
2.34.1

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+a81f27...@syzkaller.appspotmail.com

Tested on:

commit: 2668e3ae Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree: upstream

console output: https://syzkaller.appspot.com/x/log.txt?x=113f5af5180000

kernel config: https://syzkaller.appspot.com/x/.config?x=87a805e655619c64
dashboard link: https://syzkaller.appspot.com/bug?extid=a81f2759d022496b40ab
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=10feef00980000