Bug 102998
| Summary: | nptl sigcancel_handler ignores context pointer [third argument] | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 3 | Reporter: | John Reiser <jreiser> |
| Component: | glibc | Assignee: | Jakub Jelinek <jakub> |
| Status: | CLOSED NOTABUG | QA Contact: | Brian Brock <bbrock> |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | 3.0 | ||
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | i386 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2003-08-25 11:56:15 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
MD_FALLBACK_FRAME_STATE_FOR is part of libgcc, not glibc and needs to be able to unwind through any signal handler, not just SIGCANCEL in NPTL. Alternative to MD_FALLBACK_FRAME_STATE_FOR is providing .eh_frame unwind info for signal frames (e.g. in kernel virtual syscall page), but libgcc has to support older kernels as well, so MD_FALLBACK_FRAME_STATE_FOR needs to stay anyway. |
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030709 Description of problem: The sigcancel_handler() in nptl/init.c does not use its third argument, void *ctx, not even in the call to the __do_cancel() macro. Because of this, deeper levels of the implementation of canceling (__pthread_unwind, _Unwind_ForcedUnwind, MD_FALLBACK_FRAME_STATE_FOR, etc.) must assume where the context is. Such assumptions easily can be incorrect, for example if the kernel pushes the siginfo_t and struct ucontext onto the stack in the other order, or not contiguously with the parameters to the handler [there might be alignment optimizations, etc.] Instead, sigcancel_handler should use the ctx argument, passing it along to other levels, to allow intended flexibility of placement by the kernel, an auditing subsystem, etc. Version-Release number of selected component (if applicable): glibc-2.3.2-70 How reproducible: Always Steps to Reproduce: 1. Inspect the source for sigcancel_handler in nptl/init.c, and __do_cancel in nptl/pthreadP.h . 2. 3. Actual Results: The third argument to sigcancel_handler (the "void *ctx" which on Linux/i386 is "struct ucontext *") is not used. Expected Results: The void *ctx argument should be passed along for use by deeper levels of the implementation of canceling. Additional info: