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From: David Miller <davem@davemloft.net>
To: ebiggers@kernel.org
Cc: netdev@vger.kernel.org, isdn@linux-pingi.de,
	syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH net v2] isdn/capi: check message length in capi_write()
Date: Sat, 07 Sep 2019 17:47:59 +0200 (CEST)	[thread overview]
Message-ID: <20190907.174759.20721812747267246.davem@davemloft.net> (raw)
In-Reply-To: <20190906023637.768-1-ebiggers@kernel.org>

From: Eric Biggers <ebiggers@kernel.org>
Date: Thu,  5 Sep 2019 19:36:37 -0700

> From: Eric Biggers <ebiggers@google.com>
> 
> syzbot reported:
> 
>     BUG: KMSAN: uninit-value in capi_write+0x791/0xa90 drivers/isdn/capi/capi.c:700
>     CPU: 0 PID: 10025 Comm: syz-executor379 Not tainted 4.20.0-rc7+ #2
>     Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>     Call Trace:
>       __dump_stack lib/dump_stack.c:77 [inline]
>       dump_stack+0x173/0x1d0 lib/dump_stack.c:113
>       kmsan_report+0x12e/0x2a0 mm/kmsan/kmsan.c:613
>       __msan_warning+0x82/0xf0 mm/kmsan/kmsan_instr.c:313
>       capi_write+0x791/0xa90 drivers/isdn/capi/capi.c:700
>       do_loop_readv_writev fs/read_write.c:703 [inline]
>       do_iter_write+0x83e/0xd80 fs/read_write.c:961
>       vfs_writev fs/read_write.c:1004 [inline]
>       do_writev+0x397/0x840 fs/read_write.c:1039
>       __do_sys_writev fs/read_write.c:1112 [inline]
>       __se_sys_writev+0x9b/0xb0 fs/read_write.c:1109
>       __x64_sys_writev+0x4a/0x70 fs/read_write.c:1109
>       do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
>       entry_SYSCALL_64_after_hwframe+0x63/0xe7
>     [...]
> 
> The problem is that capi_write() is reading past the end of the message.
> Fix it by checking the message's length in the needed places.
> 
> Reported-and-tested-by: syzbot+0849c524d9c634f5ae66@syzkaller.appspotmail.com
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Applied and queued up for -stable.

      reply	other threads:[~2019-09-07 15:48 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-11 22:03 KMSAN: uninit-value in capi_write syzbot
2019-09-01 14:32 ` [PATCH net] isdn/capi: check message length in capi_write() Eric Biggers
2019-09-01 18:44   ` David Miller
2019-09-06  2:36     ` [PATCH net v2] " Eric Biggers
2019-09-07 15:47       ` David Miller [this message]

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