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Date: Fri, 22 Oct 2010 11:39:42 -0700 From: Greg KH <gregkh@...e.de> To: linux-kernel@...r.kernel.org, stable@...nel.org Cc: stable-review@...nel.org, torvalds@...ux-foundation.org, akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk, Roland McGrath <roland@...hat.com>, Chuck Ebbert <cebbert@...hat.com> Subject: [17/17] execve: make responsive to SIGKILL with large arguments 2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Roland McGrath <roland@...hat.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@...hat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> Cc: Chuck Ebbert <cebbert@...hat.com> Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org> --- fs/exec.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/fs/exec.c +++ b/fs/exec.c @@ -393,6 +393,9 @@ static int count(char __user * __user * argv++; if(++i > max) return -E2BIG; + + if (fatal_signal_pending(current)) + return -ERESTARTNOHAND; cond_resched(); } } @@ -436,6 +439,10 @@ 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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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