Re: [PATCH v2 1/5] exec: Only compute current once in flush_old_exec
From: Kees Cook <hidden>
Date: 2020-03-10 20:18:01
Also in:
linux-doc, linux-fsdevel, linux-mm, lkml, stable
Possibly related (same subject, not in this thread)
- 2020-03-09 · Re: [PATCH v2 1/5] exec: Only compute current once in flush_old_exec · Bernd Edlinger <hidden>
- 2020-03-09 · Re: [PATCH v2 1/5] exec: Only compute current once in flush_old_exec · Bernd Edlinger <hidden>
- 2020-03-09 · Re: [PATCH v2 1/5] exec: Only compute current once in flush_old_exec · Eric W. Biederman <hidden>
On Sun, Mar 08, 2020 at 04:35:26PM -0500, Eric W. Biederman wrote:
Make it clear that current only needs to be computed once in flush_old_exec. This may have some efficiency improvements and it makes the code easier to change. Signed-off-by: "Eric W. Biederman" <redacted>
modulo my suggestion of adding more comments (it could even be kerndoc!) that explicitly states that "me" should always be "current", yup, looks good: Reviewed-by: Kees Cook <redacted> -Kees
quoted hunk ↗ jump to hunk
--- fs/exec.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)diff --git a/fs/exec.c b/fs/exec.c index db17be51b112..c3f34791f2f0 100644 --- a/fs/exec.c +++ b/fs/exec.c@@ -1260,13 +1260,14 @@ void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec) */ int flush_old_exec(struct linux_binprm * bprm) { + struct task_struct *me = current; int retval; /* * Make sure we have a private signal table and that * we are unassociated from the previous thread group. */ - retval = de_thread(current); + retval = de_thread(me); if (retval) goto out;@@ -1294,10 +1295,10 @@ int flush_old_exec(struct linux_binprm * bprm) bprm->mm = NULL; set_fs(USER_DS); - current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | + me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE | PF_NO_SETAFFINITY); flush_thread(); - current->personality &= ~bprm->per_clear; + me->personality &= ~bprm->per_clear; /* * We have to apply CLOEXEC before we change whether the process is@@ -1305,7 +1306,7 @@ int flush_old_exec(struct linux_binprm * bprm) * trying to access the should-be-closed file descriptors of a process * undergoing exec(2). */ - do_close_on_exec(current->files); + do_close_on_exec(me->files); return 0; out:-- 2.25.0
-- Kees Cook