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coredump: treat RLIMIT_CORE below page size as disabling coredumps (#3932)

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The kernel treats values below a certain threshold (minfmt->min_coredump
which is initialized do ELF_EXEC_PAGESIZE, which varies between architectures,
but is usually the same as PAGE_SIZE) as disabling coredumps [1].
Any core image below ELF_EXEC_PAGESIZE will yield an invalid backtrace anyway [2],
so follow the kernel and not try to parse or store such images.

[1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/fs/coredump.c#n660
[2] systemd-coredump[16260]: Process 16258 (sleep) of user 1002 dumped core.
                                Stack trace of thread 16258:
                                #0  0x00007f1d8b3d3810 n/a (n/a)

https://bugzilla.redhat.com/show_bug.cgi?id=1309172#c19
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2016-08-11 04:51:00 -04:00 committed by Lennart Poettering
parent ff0bb1ed93
commit 6998b54093
1 changed files with 5 additions and 3 deletions
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8
src/coredump/coredump.c
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@ -327,9 +327,11 @@ static int save_external_coredump(
r = safe_atou64(context[CONTEXT_RLIMIT], &rlimit);
if (r < 0)
return log_error_errno(r, "Failed to parse resource limit: %s", context[CONTEXT_RLIMIT]);
if (rlimit <= 0) {
/* Is coredumping disabled? Then don't bother saving/processing the coredump */
log_info("Core Dumping has been disabled for process %s (%s).", context[CONTEXT_PID], context[CONTEXT_COMM]);
if (rlimit < page_size()) {
/* Is coredumping disabled? Then don't bother saving/processing the coredump.
* Anything below PAGE_SIZE cannot give a readable coredump (the kernel uses
* ELF_EXEC_PAGESIZE which is not easily accessible, but is usually the same as PAGE_SIZE. */
log_info("Core dumping has been disabled for process %s (%s).", context[CONTEXT_PID], context[CONTEXT_COMM]);
return -EBADSLT;
}