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authorAmanieu d'Antras <amanieu@gmail.com>2015-08-06 15:46:29 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-08-07 04:39:40 +0300
commit26135022f85105ad725cda103fa069e29e83bd16 (patch)
tree5e4f34c68105b76a88b96c467be46994d70fa5f8
parent3c00cb5e68dc719f2fc73a33b1b230aadfcb1309 (diff)
downloadlinux-stericsson-26135022f85105ad725cda103fa069e29e83bd16.tar.gz
signal: fix information leak in copy_siginfo_to_user
This function may copy the si_addr_lsb, si_lower and si_upper fields to user mode when they haven'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> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/arm64/kernel/signal32.c3
-rw-r--r--kernel/signal.c9
2 files changed, 8 insertions, 4 deletions
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index 81fd38f4fbaa..948f0ad2de23 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -168,7 +168,8 @@ int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from)
* Other callers might not initialize the si_lsb field,
* so check explicitely for the right codes here.
*/
- if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
+ if (from->si_signo == SIGBUS &&
+ (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO))
err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
#endif
break;
diff --git a/kernel/signal.c b/kernel/signal.c
index 00524cf6c412..0f6bbbe77b46 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2748,12 +2748,15 @@ int copy_siginfo_to_user(siginfo_t __user *to, const siginfo_t *from)
* Other callers might not initialize the si_lsb field,
* so check explicitly for the right codes here.
*/
- if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
+ if (from->si_signo == SIGBUS &&
+ (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO))
err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
#endif
#ifdef SEGV_BNDERR
- err |= __put_user(from->si_lower, &to->si_lower);
- err |= __put_user(from->si_upper, &to->si_upper);
+ if (from->si_signo == SIGSEGV && from->si_code == SEGV_BNDERR) {
+ err |= __put_user(from->si_lower, &to->si_lower);
+ err |= __put_user(from->si_upper, &to->si_upper);
+ }
#endif
break;
case __SI_CHLD: