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| author | Amanieu d'Antras <amanieu@gmail.com> | 2015-08-06 15:46:29 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-08-07 04:39:40 +0300 |
| commit | 26135022f85105ad725cda103fa069e29e83bd16 (patch) | |
| tree | 5e4f34c68105b76a88b96c467be46994d70fa5f8 /kernel/signal.c | |
| parent | 3c00cb5e68dc719f2fc73a33b1b230aadfcb1309 (diff) | |
| download | lwn-26135022f85105ad725cda103fa069e29e83bd16.tar.gz lwn-26135022f85105ad725cda103fa069e29e83bd16.zip | |
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>
Diffstat (limited to 'kernel/signal.c')
| -rw-r--r-- | kernel/signal.c | 9 |
1 files changed, 6 insertions, 3 deletions
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: |