[lkml]   [2007]   [Nov]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH] core dump: remain dumpable

The coredump code always calls set_dumpable(0) when it starts (even
if RLIMIT_CORE prevents any core from being dumped). The effect of
this (via task_dumpable) is to make /proc/pid/* files owned by root
instead of the user, so the user can no longer examine his own
process--in a case where there was never any privileged data to
protect. This affects e.g. auxv, environ, fd; in Fedora (execshield)
kernels, also maps. In practice, you can only notice this when a
debugger has requested PTRACE_EVENT_EXIT tracing.

set_dumpable was only used in do_coredump for synchronization and not
intended for any security purpose. (It doesn't secure anything that wasn't
already unsecured when a process dies by SIGTERM instead of SIGQUIT.)

This changes do_coredump to check the core_waiters count as the means of
synchronization, which is sufficient. Now we leave the "dumpable" bits alone.

Signed-off-by: Roland McGrath <>
fs/exec.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 2c942e2..3f70c3e 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1692,7 +1692,10 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
if (!binfmt || !binfmt->core_dump)
goto fail;
- if (!get_dumpable(mm)) {
+ /*
+ * If another thread got here first, or we are not dumpable, bail out.
+ */
+ if (mm->core_waiters || !get_dumpable(mm)) {
goto fail;
@@ -1706,7 +1709,6 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
flag = O_EXCL; /* Stop rewrite attacks */
current->fsuid = 0; /* Dump root private */
- set_dumpable(mm, 0);

retval = coredump_wait(exit_code);
if (retval < 0)
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at
 \ /
  Last update: 2007-11-12 04:17    [W:0.067 / U:0.952 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site