[release/10.0] Check for SIG_IGN and SIG_DFL before calling previous signal handler - #133177
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…132900) macOS doesn't clear sa_flags when calling execve. When dotnet is started from a process that sets a signal handler, the handler is cleared, but not the sa_flags. When the runtime gets a signal from an external source, it sees a stale SA_SIGINGO and tries to call the previous signal handler, but the pointer is set to SIG_IGN or SIG_DFL, which causes a crash. This change checks for those values before calling the previous signal handler. Also adds a regression test for the issue. Fixes #132581 --------- Co-authored-by: Jan Kotas <jkotas@microsoft.com>
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jkotas
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Sep 3, 2026
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/ba-g known issues on system.net. |
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Backport of #132900 to release/10.0
/cc @jtschuster
Customer Impact
macOS doesn't clear sa_flags when calling execve. When dotnet is started from a process that sets a signal handler, the handler is cleared, but not the sa_flags. When the runtime gets a signal from an external source, it sees a stale SA_SIGINGO and tries to call the previous signal handler, but the pointer is set to SIG_IGN or SIG_DFL, which causes a segmentation fault and crashes the process. This change checks for those values before calling the previous signal handler. Also adds a regression test for the issue.
Regression
Testing
The issue was reproduced in a regression test that was added to coreclr tests. The test fails without the fix and passes with it.
Risk
Low. The actual source change is small and targeted.