[PATCH v3 2/2] kexec: fix error propagation in kexec_image_probe_default()

[Mukesh Pilaniya]

kexec_image_probe_default() overwrites ret with each loader's probe
return value and returns whatever the last loader returned when no
probe matches.  The error code reaching userspace depends on whichever
loader happens to be last in kexec_file_loaders[].

Only continue to the next loader when a probe returns -ENOEXEC.
Propagate any other error such as -ENOMEM immediately. Return -ENOEXEC
only when all loaders have been tried and none matched.

Suggested-by: Pratyush Yadav <pratyush at kernel.org>
Signed-off-by: Mukesh Pilaniya <mpilaniy at redhat.com>
Reviewed-by: Pratyush Yadav <pratyush at kernel.org>
Reviewed-by: Philipp Rudo <prudo at redhat.com>
---
 kernel/kexec_file.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 59fb9d71e9d8..c11a815e2235 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -68,17 +68,19 @@ int kexec_image_probe_default(struct kimage *image, void *buf,
 			      unsigned long buf_len)
 {
 	const struct kexec_file_ops * const *fops;
-	int ret = -ENOEXEC;
 
 	for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) {
-		ret = (*fops)->probe(buf, buf_len);
-		if (!ret) {
+		int err = (*fops)->probe(buf, buf_len);
+
+		if (!err) {
 			image->fops = *fops;
-			return ret;
+			return 0;
 		}
+		if (err != -ENOEXEC)
+			return err;
 	}
 
-	return ret;
+	return -ENOEXEC;
 }
 
 static void *kexec_image_load_default(struct kimage *image)

-- 
Git-155)