37 lines
1.4 KiB
Diff
37 lines
1.4 KiB
Diff
Emergency backport of this change prior to upstream acceptance:
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Wed May 26 07:13:00 2021 +0200
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nptl: Install SIGSETXID handler with SA_ONSTACK [BZ #27914]
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The signal is sent to all threads, some of which may have switched
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to very small stacks. If they have also installed an alternate
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signal stack, SA_ONSTACK makes this work. The Go runtime needs this:
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runtime: C.setuid/C.setgid smashes Go stack
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<https://github.com/golang/go/issues/9400>
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Doing this for SIGCANCEL is less obviously beneficial and needs further
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testing.
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diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
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index 5680687efe7089da..b7073a828549d24c 100644
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--- a/nptl/pthread_create.c
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+++ b/nptl/pthread_create.c
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@@ -83,9 +83,12 @@ late_init (void)
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(void) __libc_sigaction (SIGCANCEL, &sa, NULL);
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}
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- /* Install the handle to change the threads' uid/gid. */
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+ /* Install the handle to change the threads' uid/gid. Use
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+ SA_ONSTACK because the signal may be sent to threads that are
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+ running with custom stacks. (This is less likely for
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+ SIGCANCEL.) */
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sa.sa_sigaction = __nptl_setxid_sighandler;
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- sa.sa_flags = SA_SIGINFO | SA_RESTART;
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+ sa.sa_flags = SA_ONSTACK | SA_SIGINFO | SA_RESTART;
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(void) __libc_sigaction (SIGSETXID, &sa, NULL);
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/* The parent process might have left the signals blocked. Just in
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