Bug 224131
| Summary: | No zero holes for PTRACE_PEEKUSR/PTRACE_POKEUSR? | ||||||
|---|---|---|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 5 | Reporter: | Alexey Dobriyan <adobriyan> | ||||
| Component: | kernel | Assignee: | Roland McGrath <roland> | ||||
| Status: | CLOSED ERRATA | QA Contact: | Brian Brock <bbrock> | ||||
| Severity: | medium | Docs Contact: | |||||
| Priority: | medium | ||||||
| Version: | 5.0 | CC: | dzickus, petrides | ||||
| Target Milestone: | --- | ||||||
| Target Release: | --- | ||||||
| Hardware: | i386 | ||||||
| OS: | Linux | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | RHBA-2007-0959 | Doc Type: | Bug Fix | ||||
| Doc Text: | Story Points: | --- | |||||
| Clone Of: | Environment: | ||||||
| Last Closed: | 2007-11-07 19:21:59 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: | |||||||
| Attachments: |
|
||||||
Created attachment 146399 [details]
Third segment in i386_uarea
Don, this problem was fixed in linux-2.6-misc-utrace-update.patch (in the RHEL-5 CVS repo). I couldn't find the corresponding patch tracking file. Please add this BZ to the RHEL5.1 advisory. An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHBA-2007-0959.html |
I wonder why "i386_uarea" array contains only two segments? arch/i386/kernel/ptrace.c: 735 static const struct ptrace_layout_segment i386_uarea[] = { 736 {0, FRAME_SIZE*4, 0, 0}, 737 {offsetof(struct user, u_debugreg[0]), 738 offsetof(struct user, u_debugreg[8]), 4, 0}, 739 {0, 0, -1, 0} 740 }; If ptrace is ptrace, ptrace(PTRACE_PEEKUSR, addr, ...) would return 0 for accesses in hole. If ptrace is utrace it would return -EIO, for same accesses. strace(1) notices this when seeing unknown syscall. On i386 it checks MAX_ARGS (32) args, and gets -EIO on 17-th: syscall.c: 2161 if (tcp->scno >= 0 && tcp->scno < nsyscalls && sysent[tcp->scno].nargs != -1) 2162 tcp->u_nargs = sysent[tcp->scno].nargs; 2163 else 2164 tcp->u_nargs = MAX_ARGS; 2165 for (i = 0; i < tcp->u_nargs; i++) { 2166 if (upeek(pid, i*4, &tcp->u_arg[i]) < 0) 2167 return -1; 2168 }