From: Eric Biggers <ebigg...@kernel.org> Date: Thu, 5 Sep 2019 19:36:37 -0700
> From: Eric Biggers <ebigg...@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+0849c524d9c634f5a...@syzkaller.appspotmail.com > Signed-off-by: Eric Biggers <ebigg...@google.com> Applied and queued up for -stable.
