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| author | Kees Cook <keescook@chromium.org> | 2017-03-23 15:46:16 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-03-24 07:43:35 +0100 |
| commit | 854fbd6e5f60fe99e8e3a569865409fca378f143 (patch) | |
| tree | 7f0d56d40169921ca321b22a5c3f7074569ec52e | |
| parent | ebe64824e9de4b3ab3bd3928312b4b2bc57b4b7e (diff) | |
| download | linux-854fbd6e5f60fe99e8e3a569865409fca378f143.tar.bz2 | |
lib/syscall: Clear return values when no stack
Commit:
aa1f1a639621 ("lib/syscall: Pin the task stack in collect_syscall()")
... added logic to handle a process stack not existing, but left sp and pc
uninitialized, which can be later reported via /proc/$pid/syscall for zombie
processes, potentially exposing kernel memory to userspace.
Zombie /proc/$pid/syscall before:
-1 0xffffffff9a060100 0xffff92f42d6ad900
Zombie /proc/$pid/syscall after:
-1 0x0 0x0
Reported-by: Robert Święcki <robert@swiecki.net>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org # v4.9+
Fixes: aa1f1a639621 ("lib/syscall: Pin the task stack in collect_syscall()")
Link: http://lkml.kernel.org/r/20170323224616.GA92694@beast
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | lib/syscall.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/lib/syscall.c b/lib/syscall.c index 17d5ff5fa6a3..2c6cd1b5c3ea 100644 --- a/lib/syscall.c +++ b/lib/syscall.c @@ -12,6 +12,7 @@ static int collect_syscall(struct task_struct *target, long *callno, if (!try_get_task_stack(target)) { /* Task has no stack, so the task isn't in a syscall. */ + *sp = *pc = 0; *callno = -1; return 0; } |