Commit 3ead7c52 authored by Amanieu d'Antras's avatar Amanieu d'Antras Committed by Linus Torvalds

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: default avatarAmanieu d'Antras <amanieu@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 26135022
......@@ -121,8 +121,9 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
* Other callers might not initialize the si_lsb field,
* so check explicitly for the right codes here.
*/
if (kinfo->si_code == BUS_MCEERR_AR ||
kinfo->si_code == BUS_MCEERR_AO)
if (kinfo->si_signo == SIGBUS &&
(kinfo->si_code == BUS_MCEERR_AR ||
kinfo->si_code == BUS_MCEERR_AO))
err |= __put_user((short) kinfo->si_addr_lsb,
&uinfo->ssi_addr_lsb);
#endif
......
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