From: Roland McGrath Date: Wed, 8 Sep 2010 02:37:06 +0000 (-0700) Subject: execve: make responsive to SIGKILL with large arguments X-Git-Tag: v2.6.33.8~432 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fe6595caaea6d84fd1290df4dfe762235bd7662b;p=thirdparty%2Fkernel%2Fstable.git execve: make responsive to SIGKILL with large arguments 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 Reviewed-by: KOSAKI Motohiro Cc: Chuck Ebbert Signed-off-by: Linus Torvalds --- diff --git a/fs/exec.c b/fs/exec.c index 982c3c8473c04..3132722205a35 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -375,6 +375,9 @@ static int count(char __user * __user * argv, int max) argv++; if (i++ >= max) return -E2BIG; + + if (fatal_signal_pending(current)) + return -ERESTARTNOHAND; cond_resched(); } } @@ -418,6 +421,10 @@ static int copy_strings(int argc, char __user * __user * argv, while (len > 0) { int offset, bytes_to_copy; + if (fatal_signal_pending(current)) { + ret = -ERESTARTNOHAND; + goto out; + } cond_resched(); offset = pos % PAGE_SIZE;