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| author | Denys Vlasenko <vda.linux@googlemail.com> | 2012-03-23 15:02:40 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-03-23 16:58:40 -0700 |
| commit | 8c5cf9e5c50dc902713897e10201aa71f3546aa1 (patch) | |
| tree | 9d5590690c0bf2b596697768972b8d42de2e8a28 | |
| parent | b1845ff53f1a9eadba005ae53dfe60ab00dfe83b (diff) | |
| download | lwn-8c5cf9e5c50dc902713897e10201aa71f3546aa1.tar.gz lwn-8c5cf9e5c50dc902713897e10201aa71f3546aa1.zip | |
ptrace: don't modify flags on PTRACE_SETOPTIONS failure
On ptrace(PTRACE_SETOPTIONS, pid, 0, <opts>), we used to set those
option bits which are known, and then fail with -EINVAL if there are
some unknown bits in <opts>.
This is inconsistent with typical error handling, which does not change
any state if input is invalid.
This patch changes PTRACE_SETOPTIONS behavior so that in this case, we
return -EINVAL and don't change any bits in task->ptrace.
It's very unlikely that there is userspace code in the wild which will
be affected by this change: it should have the form
ptrace(PTRACE_SETOPTIONS, pid, 0, PTRACE_O_BOGUSOPT)
where PTRACE_O_BOGUSOPT is a constant unknown to the kernel. But kernel
headers, naturally, don't contain any PTRACE_O_BOGUSOPTs, thus the only
way userspace can use one if it defines one itself. I can't see why
anyone would do such a thing deliberately.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | kernel/ptrace.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 00ab2ca5ed11..273f56ea39d2 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -528,6 +528,9 @@ int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long ds static int ptrace_setoptions(struct task_struct *child, unsigned long data) { + if (data & ~(unsigned long)PTRACE_O_MASK) + return -EINVAL; + child->ptrace &= ~PT_TRACE_MASK; if (data & PTRACE_O_TRACESYSGOOD) @@ -551,7 +554,7 @@ static int ptrace_setoptions(struct task_struct *child, unsigned long data) if (data & PTRACE_O_TRACEEXIT) child->ptrace |= PT_TRACE_EXIT; - return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; + return 0; } static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info) |