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authorAmanieu d'Antras <amanieu@gmail.com>2015-08-06 15:46:29 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-08-16 20:51:51 -0700
commitd096e80771d3a68dbb559140a0b4c475ee5051cd (patch)
tree1ce7205b897f31a6313d8800a4cf57efcbed15ba
parentfda4653f0dd865a7d54ad53825cc74e15b75f70d (diff)
signal: fix information leak in copy_siginfo_to_user
commit 26135022f85105ad725cda103fa069e29e83bd16 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/arm64/kernel/signal32.c3
-rw-r--r--kernel/signal.c3
2 files changed, 4 insertions, 2 deletions
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index 7ed72dc0fb0e..624e993a4a06 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -165,7 +165,8 @@ 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 52f881db1ca0..7e44cdf43cc1 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2768,7 +2768,8 @@ 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
break;