On Mon, Dec 30, 2024 at 11:17:30AM +0100, Nam Cao wrote: > The field "eip" (instruction pointer) and "esp" (stack pointer) of a task > can be read from /proc/PID/stat. These fields can be interesting for > coredump. > > However, these fields were disabled by commit 0a1eb2d474ed ("fs/proc: Stop > reporting eip and esp in /proc/PID/stat"), because it is generally unsafe > to do so. But it is safe for a coredumping process, and therefore > exceptions were made: > > - for a coredumping thread by commit fd7d56270b52 ("fs/proc: Report > eip/esp in /prod/PID/stat for coredumping"). > > - for all other threads in a coredumping process by commit cb8f381f1613 > ("fs/proc/array.c: allow reporting eip/esp for all coredumping > threads"). > > The above two commits check the PF_DUMPCORE flag to determine a coredump thread > and the PF_EXITING flag for the other threads. > > Unfortunately, commit 92307383082d ("coredump: Don't perform any cleanups > before dumping core") moved coredump to happen earlier and before PF_EXITING is > set. Thus, checking PF_EXITING is no longer the correct way to determine > threads in a coredumping process. > > Instead of PF_EXITING, use PF_POSTCOREDUMP to determine the other threads. > > Checking of PF_EXITING was added for coredumping, so it probably can now be > removed. But it doesn't hurt to keep. > > Fixes: 92307383082d ("coredump: Don't perform any cleanups before dumping core") > Cc: stable@xxxxxxxxxxxxxxx > Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> > Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx> > Signed-off-by: Nam Cao <namcao@xxxxxxxxxxxxx> Thanks for fixing this! Acked-by: Kees Cook <kees@xxxxxxxxxx> -- Kees Cook