Bug 20065
| Summary: | sigcontext mismatch? | ||
|---|---|---|---|
| Product: | [Retired] Red Hat Linux | Reporter: | Len Widra <lenwidra> |
| Component: | kernel | Assignee: | Arjan van de Ven <arjanv> |
| Status: | CLOSED CURRENTRELEASE | QA Contact: | Brian Brock <bbrock> |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | 9 | ||
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | i686 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2004-09-30 15:38:51 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: | |||
Example still works on RH9. Needs review to verify if it is in fact correct or not Thanks for the bug report. However, Red Hat no longer maintains this version of the product. Please upgrade to the latest version and open a new bug if the problem persists. The Fedora Legacy project (http://fedoralegacy.org/) maintains some older releases, and if you believe this bug is interesting to them, please report the problem in the bug tracker at: http://bugzilla.fedora.us/ |
For x86 platforms, it seems like there's a mismatch between 1) the sigcontext structure defined in RH 7.0 /usr/include/asm/sigcontext.h and 2) the structure that is actually pushed as the third argument to a signal handler. As a result, the "offending PC" ends up in the "fpstate" member rather than in "cr2", where it's presumably supposed to be. I haven't found a man page description for the third arg passed to a signal handler, so it's hard to be certain what's intended. "man sigaction" just shows this arg as a "void *" with no further explanation. Below is illustrative test code. #include <sys/ucontext.h> #define SIGCONTEXTPC fpstate /* Actually, the PC! */ void fatal_signal_error_handler(int signo, siginfo_t *sinfo, void *pcontext) { char PCbuf[32]; struct sigcontext *context = pcontext; printf("pid %d sees signal %d\n", getpid(), signo); printf("si_code is 0x%x\n", sinfo->si_code); printf("si_addr is 0x%x\n", (long)(sinfo->si_addr)); sprintf(PCbuf, "0x%x", context->SIGCONTEXTPC); printf("offending PC is %s\n", PCbuf); sleep(100000); /* Allow gdb to be used on running process */ } void set_signals() { int sig; struct sigaction sigact; sigact.sa_sigaction = fatal_signal_error_handler; sigemptyset(&sigact.sa_mask); sigact.sa_flags = SA_SIGINFO; sigact.sa_restorer = 0; sigaction(SIGSEGV, &sigact, 0); } main() { char *badaddr = (char *)0x37; int x; set_signals(); x = *badaddr; }