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authorJohn Ogness <john.ogness@linutronix.de>2017-09-14 11:42:17 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-10-05 09:43:58 +0200
commit9ad15a25669ec8c120e910cf18620af2455cb6df (patch)
treed27acd17a498798f3df3f60696a9d3fce81d75dc /fs
parentb6a77c7ba6741240d7bbf5b520e6eb93d3a5b211 (diff)
fs/proc: Report eip/esp in /prod/PID/stat for coredumping
commit fd7d56270b526ca3ed0c224362e3c64a0f86687a upstream. Commit 0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in /proc/PID/stat") stopped reporting eip/esp because it is racy and dangerous for executing tasks. The comment adds: As far as I know, there are no use programs that make any material use of these fields, so just get rid of them. However, existing userspace core-dump-handler applications (for example, minicoredumper) are using these fields since they provide an excellent cross-platform interface to these valuable pointers. So that commit introduced a user space visible regression. Partially revert the change and make the readout possible for tasks with the proper permissions and only if the target task has the PF_DUMPCORE flag set. Fixes: 0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in> /proc/PID/stat") Reported-by: Marco Felsch <marco.felsch@preh.de> Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Andy Lutomirski <luto@kernel.org> Cc: Tycho Andersen <tycho.andersen@canonical.com> Cc: Kees Cook <keescook@chromium.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Brian Gerst <brgerst@gmail.com> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Borislav Petkov <bp@alien8.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Linux API <linux-api@vger.kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/87poatfwg6.fsf@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/proc/array.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 81818adb8e9e..c932ec454625 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -60,6 +60,7 @@
#include <linux/tty.h>
#include <linux/string.h>
#include <linux/mman.h>
+#include <linux/sched.h>
#include <linux/proc_fs.h>
#include <linux/ioport.h>
#include <linux/uaccess.h>
@@ -416,7 +417,15 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
* esp and eip are intentionally zeroed out. There is no
* non-racy way to read them without freezing the task.
* Programs that need reliable values can use ptrace(2).
+ *
+ * The only exception is if the task is core dumping because
+ * a program is not able to use ptrace(2) in that case. It is
+ * safe because the task has stopped executing permanently.
*/
+ if (permitted && (task->flags & PF_DUMPCORE)) {
+ eip = KSTK_EIP(task);
+ esp = KSTK_ESP(task);
+ }
}
get_task_comm(tcomm, task);