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Subject[102/103] execve: make responsive to SIGKILL with large arguments
2.6.35-stable review patch.  If anyone has any objections, please let us know.


From: Roland McGrath <>

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 <>

fs/exec.c | 7 +++++++
1 file changed, 7 insertions(+)

--- a/fs/exec.c
+++ b/fs/exec.c
@@ -377,6 +377,9 @@ static int count(char __user * __user *
if (i++ >= max)
return -E2BIG;
+ if (fatal_signal_pending(current))
@@ -420,6 +423,10 @@ static int copy_strings(int argc, char _
while (len > 0) {
int offset, bytes_to_copy;

+ if (fatal_signal_pending(current)) {
+ goto out;
+ }

offset = pos % PAGE_SIZE;

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