signalfd: fix information leak in signalfd_copyinfo
authorAmanieu d'Antras <amanieu@gmail.com>
Thu, 6 Aug 2015 22:46:33 +0000 (15:46 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 7 Aug 2015 01:39:40 +0000 (04:39 +0300)
commit3ead7c52bdb0ab44f4bb1feed505a8323cc12ba7
tree255fa7484e68697aedfa97658a962dc804ab16f3
parent26135022f85105ad725cda103fa069e29e83bd16
signalfd: fix information leak in signalfd_copyinfo

This function may copy the si_addr_lsb field to user mode when it hasn't
been initialized, which can leak kernel stack data to user mode.

Just checking the value of si_code is insufficient because the same
si_code value is shared between multiple signals.  This is solved by
checking the value of si_signo in addition to si_code.

Signed-off-by: Amanieu d'Antras <amanieu@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/signalfd.c