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exec: Don't open code get_close_on_exec 

Al Viro pointed out that using the phrase "close_on_exec(fd,
rcu_dereference_raw(current->files->fdt))" instead of wrapping it in
rcu_read_lock(), rcu_read_unlock() is a very questionable
optimization[1].

Once wrapped with rcu_read_lock()/rcu_read_unlock() that phrase
becomes equivalent the helper function get_close_on_exec so
simplify the code and make it more robust by simply using
get_close_on_exec.

[1] https://lkml.kernel.org/r/20201207222214.GA4115853@ZenIV.linux.org.uk
Suggested-by: Al Viro <viro@ftp.linux.org.uk>
Link: https://lkml.kernel.org/r/87k0tqr6zi.fsf_-_@x220.int.ebiederm.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2020-12-09 15:42:57 -06:00
parent 3650b228f8
commit 878f12dbb8
1 changed files with 1 additions and 2 deletions
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3
fs/exec.c
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@ -1808,8 +1808,7 @@ static int bprm_execve(struct linux_binprm *bprm,
* inaccessible after exec. Relies on having exclusive access to * inaccessible after exec. Relies on having exclusive access to
* current->files (due to unshare_files above). * current->files (due to unshare_files above).
*/ */
if (bprm->fdpath && if (bprm->fdpath && get_close_on_exec(fd))
close_on_exec(fd, rcu_dereference_raw(current->files->fdt)))
bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE; bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
/* Set the unchanging part of bprm->cred */ /* Set the unchanging part of bprm->cred */