1 files changed, 21 insertions, 22 deletions

diff --git a/fs/exec.c b/fs/exec.c
index a47d0e4c54f6..caae051c5a95 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -145,13 +145,11 @@ SYSCALL_DEFINE1(uselib, const char __user *, library)
 		goto out;
 
 	/*
-	 * may_open() has already checked for this, so it should be
-	 * impossible to trip now. But we need to be extra cautious
-	 * and check again at the very end too.
+	 * Check do_open_execat() for an explanation.
 	 */
 	error = -EACCES;
-	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
-			 path_noexec(&file->f_path)))
+	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode)) ||
+	    path_noexec(&file->f_path))
 		goto exit;
 
 	error = -ENOEXEC;
@@ -954,7 +952,6 @@ EXPORT_SYMBOL(transfer_args_to_stack);
 static struct file *do_open_execat(int fd, struct filename *name, int flags)
 {
 	struct file *file;
-	int err;
 	struct open_flags open_exec_flags = {
 		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 		.acc_mode = MAY_EXEC,
@@ -971,24 +968,20 @@ static struct file *do_open_execat(int fd, struct filename *name, int flags)
 
 	file = do_filp_open(fd, name, &open_exec_flags);
 	if (IS_ERR(file))
-		goto out;
+		return file;
 
 	/*
-	 * may_open() has already checked for this, so it should be
-	 * impossible to trip now. But we need to be extra cautious
-	 * and check again at the very end too.
+	 * In the past the regular type check was here. It moved to may_open() in
+	 * 633fb6ac3980 ("exec: move S_ISREG() check earlier"). Since then it is
+	 * an invariant that all non-regular files error out before we get here.
 	 */
-	err = -EACCES;
-	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
-			 path_noexec(&file->f_path)))
-		goto exit;
+	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode)) ||
+	    path_noexec(&file->f_path)) {
+		fput(file);
+		return ERR_PTR(-EACCES);
+	}
 
-out:
 	return file;
-
-exit:
-	fput(file);
-	return ERR_PTR(err);
 }
 
 /**
@@ -1692,6 +1685,7 @@ static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
 	unsigned int mode;
 	vfsuid_t vfsuid;
 	vfsgid_t vfsgid;
+	int err;
 
 	if (!mnt_may_suid(file->f_path.mnt))
 		return;
@@ -1708,12 +1702,17 @@ static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
 	/* Be careful if suid/sgid is set */
 	inode_lock(inode);
 
-	/* reload atomically mode/uid/gid now that lock held */
+	/* Atomically reload and check mode/uid/gid now that lock held. */
 	mode = inode->i_mode;
 	vfsuid = i_uid_into_vfsuid(idmap, inode);
 	vfsgid = i_gid_into_vfsgid(idmap, inode);
+	err = inode_permission(idmap, inode, MAY_EXEC);
 	inode_unlock(inode);
 
+	/* Did the exec bit vanish out from under us? Give up. */
+	if (err)
+		return;
+
 	/* We ignore suid/sgid if there are no mappings for them in the ns */
 	if (!vfsuid_has_mapping(bprm->cred->user_ns, vfsuid) ||
 	    !vfsgid_has_mapping(bprm->cred->user_ns, vfsgid))
@@ -2204,7 +2203,7 @@ COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
 
 #ifdef CONFIG_SYSCTL
 
-static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write,
+static int proc_dointvec_minmax_coredump(const struct ctl_table *table, int write,
 		void *buffer, size_t *lenp, loff_t *ppos)
 {
 	int error = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
@@ -2236,5 +2235,5 @@ fs_initcall(init_fs_exec_sysctls);
 #endif /* CONFIG_SYSCTL */
 
 #ifdef CONFIG_EXEC_KUNIT_TEST
-#include "exec_test.c"
+#include "tests/exec_kunit.c"
 #endif