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: v2.6.36-rc4~12 X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=9aea5a65aa7a1af9a4236dfaeb0088f1624f9919 execve: make responsive to SIGKILL with large arguments 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 Signed-off-by: Linus Torvalds --- diff --git a/fs/exec.c b/fs/exec.c index 6f2d777..828dd24 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -376,6 +376,9 @@ static int count(const char __user * const __user * argv, int max) 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, const char __user *const __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;