4.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Amanieu d'Antras <aman...@gmail.com>
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 <aman...@gmail.com>
Cc: Oleg Nesterov <o...@redhat.com>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Russell King <r...@arm.linux.org.uk>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/arm64/kernel/signal32.c | 3 ++-
kernel/signal.c | 9 ++++++---
2 files changed, 8 insertions(+), 4 deletions(-)
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -168,7 +168,8 @@ int copy_siginfo_to_user32(compat_siginf
* 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;
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2753,12 +2753,15 @@ int copy_siginfo_to_user(siginfo_t __use
* 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:
--
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