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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 <roland@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -376,6 +376,9 @@ static int count(const char __user * const __user * argv, int max)
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argv++;
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if (i++ >= max)
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return -E2BIG;
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if (fatal_signal_pending(current))
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return -ERESTARTNOHAND;
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cond_resched();
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}
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}
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@ -419,6 +422,10 @@ static int copy_strings(int argc, const char __user *const __user *argv,
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while (len > 0) {
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int offset, bytes_to_copy;
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if (fatal_signal_pending(current)) {
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ret = -ERESTARTNOHAND;
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goto out;
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}
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cond_resched();
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offset = pos % PAGE_SIZE;
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