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author | Neil Horman <nhorman@tuxdriver.com> | 2009-09-23 15:56:54 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-24 07:21:00 -0700 |
commit | 725eae32df7754044809973034429a47e6035158 (patch) | |
tree | 96a66c65a085940a19374ee02c26fb8f1931a6be /fs/exec.c | |
parent | ae6d2ed7bb3877ff35b9569402025f40ea2e1803 (diff) | |
download | lwn-725eae32df7754044809973034429a47e6035158.tar.gz lwn-725eae32df7754044809973034429a47e6035158.zip |
exec: make do_coredump() more resilient to recursive crashes
Change how we detect recursive dumps.
Currently we have a mechanism by which we try to compare pathnames of the
crashing process to the core_pattern path. This is broken for a dozen
reasons, and just doesn't work in any sort of robust way.
I'm replacing it with the use of a 0 RLIMIT_CORE value. Since helper apps
set RLIMIT_CORE to zero, we don't write out core files for any process
with that particular limit set. It the core_pattern is a pipe, any
non-zero limit is translated to RLIM_INFINITY.
This allows complete dumps to be captured, but prevents infinite recursion
in the event that the core_pattern process itself crashes.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Reported-by: Earl Chew <earl_chew@agilent.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/exec.c')
-rw-r--r-- | fs/exec.c | 45 |
1 files changed, 23 insertions, 22 deletions
diff --git a/fs/exec.c b/fs/exec.c index 5c833c18d0d4..735d9c18ec71 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1799,38 +1799,39 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs) lock_kernel(); ispipe = format_corename(corename, signr); unlock_kernel(); - /* - * Don't bother to check the RLIMIT_CORE value if core_pattern points - * to a pipe. Since we're not writing directly to the filesystem - * RLIMIT_CORE doesn't really apply, as no actual core file will be - * created unless the pipe reader choses to write out the core file - * at which point file size limits and permissions will be imposed - * as it does with any other process - */ + if ((!ispipe) && (core_limit < binfmt->min_coredump)) goto fail_unlock; if (ispipe) { + if (core_limit == 0) { + /* + * Normally core limits are irrelevant to pipes, since + * we're not writing to the file system, but we use + * core_limit of 0 here as a speacial value. Any + * non-zero limit gets set to RLIM_INFINITY below, but + * a limit of 0 skips the dump. This is a consistent + * way to catch recursive crashes. We can still crash + * if the core_pattern binary sets RLIM_CORE = !0 + * but it runs as root, and can do lots of stupid things + * Note that we use task_tgid_vnr here to grab the pid + * of the process group leader. That way we get the + * right pid if a thread in a multi-threaded + * core_pattern process dies. + */ + printk(KERN_WARNING + "Process %d(%s) has RLIMIT_CORE set to 0\n", + task_tgid_vnr(current), current->comm); + printk(KERN_WARNING "Aborting core\n"); + goto fail_unlock; + } + helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc); if (!helper_argv) { printk(KERN_WARNING "%s failed to allocate memory\n", __func__); goto fail_unlock; } - /* Terminate the string before the first option */ - delimit = strchr(corename, ' '); - if (delimit) - *delimit = '\0'; - delimit = strrchr(helper_argv[0], '/'); - if (delimit) - delimit++; - else - delimit = helper_argv[0]; - if (!strcmp(delimit, current->comm)) { - printk(KERN_NOTICE "Recursive core dump detected, " - "aborting\n"); - goto fail_unlock; - } core_limit = RLIM_INFINITY; |