[Bug libc/28257] New: SIGSEGV instead of EINVAL with invalid timer id in timer_delete/timer_gettime/timer_settime

[Bug libc/28257] New: SIGSEGV instead of EINVAL with invalid timer id in timer_delete/timer_gettime/timer_settime

[michael.hudson at canonical dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28257

            Bug ID: 28257
           Summary: SIGSEGV instead of EINVAL with invalid timer id in
                    timer_delete/timer_gettime/timer_settime
           Product: glibc
           Version: 2.34
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: michael.hudson at canonical dot com
                CC: drepper.fsp at gmail dot com
  Target Milestone: ---

Forwarding from https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1940296:

The timer_delete(2) man page states:

RETURN VALUE
       On success, timer_delete() returns 0. On failure, -1 is returned,
       and errno is set to indicate the error.

ERRORS
       EINVAL timerid is not a valid timer ID.

The following shows that this is not strictly true:

$ cat t.c

#include <time.h>
#include <stdlib.h>

int main(void)
{
        timer_t t = (timer_t)0xe236f38802c65008ULL;

        return timer_delete(t);
}

$ gcc t.c -lrt -g
./a.out
Segmentation fault (core dumped)

$ valgrind ./a.out
==30195== Memcheck, a memory error detector
==30195== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==30195== Using Valgrind-3.17.0 and LibVEX; rerun with -h for copyright info
==30195== Command: ./a.out
==30195==
==30195== Invalid read of size 4
==30195== at 0x487FBF7: timerid_to_kernel_timer (kernel-posix-timers.h:94)
==30195== by 0x487FBF7: timer_delete@@GLIBC_2.3.3 (timer_delete.c:35)
==30195== by 0x10916E: main (t.c:8)
==30195== Address 0xc46de710058ca010 is not stack'd, malloc'd or (recently)
free'd
==30195==
==30195==
==30195== Process terminating with default action of signal 11 (SIGSEGV)
==30195== General Protection Fault
==30195== at 0x487FBF7: timerid_to_kernel_timer (kernel-posix-timers.h:94)
==30195== by 0x487FBF7: timer_delete@@GLIBC_2.3.3 (timer_delete.c:35)
==30195== by 0x10916E: main (t.c:8)
==30195==
==30195== HEAP SUMMARY:
==30195== in use at exit: 0 bytes in 0 blocks
==30195== total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==30195==
==30195== All heap blocks were freed -- no leaks are possible
==30195==
==30195== For lists of detected and suppressed errors, rerun with: -s
==30195== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
Segmentation fault (core dumped)

Similar things happen with timer_gettime and timer_settime.

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[Bug libc/28257] SIGSEGV instead of EINVAL with invalid timer id in timer_delete/timer_gettime/timer_settime

[michael.hudson at canonical dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28257

Michael Hudson-Doyle <michael.hudson at canonical dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |michael.hudson at canonical dot co
                   |                            |m

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[Bug libc/28257] SIGSEGV instead of EINVAL with invalid timer id in timer_delete/timer_gettime/timer_settime

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28257

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |fweimer at redhat dot com
         Resolution|---                         |MOVED

--- Comment #1 from Florian Weimer <fweimer at redhat dot com> ---
Please report this to the man-pages project if the manual page is unclear.

POSIX clearly describes what the program is doing as undefined behavior:

“
The behavior is undefined if the value specified by the timerid argument to
timer_delete() does not correspond to a timer ID returned by timer_create() but
not yet deleted by timer_delete().
”

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