Messages in this thread Patch in this message | | | Date | Fri, 22 Oct 2010 11:35:30 -0700 | From | Greg KH <> | Subject | [63/66] execve: make responsive to SIGKILL with large arguments |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
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From: Roland McGrath <roland@redhat.com>
commit 9aea5a65aa7a1af9a4236dfaeb0088f1624f9919 upstream.
An execve with a very large total of argument/environment strings can take a really long time in the execve system call. It runs uninterruptibly to count and copy all the strings. This change makes it abort the exec quickly if sent a SIGKILL.
Note that this is the conservative change, to interrupt only for SIGKILL, by using fatal_signal_pending(). It would be perfectly correct semantics to let any signal interrupt the string-copying in execve, i.e. use signal_pending() instead of fatal_signal_pending(). We'll save that change for later, since it could have user-visible consequences, such as having a timer set too quickly make it so that an execve can never complete, though it always happened to work before.
Signed-off-by: Roland McGrath <roland@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Chuck Ebbert <cebbert@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
--- fs/exec.c | 7 +++++++ 1 file changed, 7 insertions(+)
--- a/fs/exec.c +++ b/fs/exec.c @@ -376,6 +376,9 @@ static int count(char __user * __user * argv++; if (i++ >= max) return -E2BIG; + + if (fatal_signal_pending(current)) + return -ERESTARTNOHAND; cond_resched(); } } @@ -419,6 +422,10 @@ static int copy_strings(int argc, char _ while (len > 0) { int offset, bytes_to_copy; + if (fatal_signal_pending(current)) { + ret = -ERESTARTNOHAND; + goto out; + } cond_resched(); offset = pos % PAGE_SIZE;
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