[PATCH 5.17 0062/1126] remoteproc: Fix count check in rproc_coredump_write()

[Greg Kroah-Hartman]

From: Alistair Delva <adelva@xxxxxxxxxx>

commit f89672cc3681952f2d06314981a6b45f8b0045d1 upstream.

Check count for 0, to avoid a potential underflow. Make the check the
same as the one in rproc_recovery_write().

Fixes: 3afdc59e4390 ("remoteproc: Add coredump debugfs entry")
Signed-off-by: Alistair Delva <adelva@xxxxxxxxxx>
Cc: Rishabh Bhatnagar <rishabhb@xxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Cc: Ohad Ben-Cohen <ohad@xxxxxxxxxx>
Cc: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Sibi Sankar <sibis@xxxxxxxxxxxxxx>
Cc: linux-remoteproc@xxxxxxxxxxxxxxx
Cc: kernel-team@xxxxxxxxxxx
Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220119232139.1125908-1-adelva@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/remoteproc/remoteproc_debugfs.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/remoteproc/remoteproc_debugfs.c
+++ b/drivers/remoteproc/remoteproc_debugfs.c
@@ -76,7 +76,7 @@ static ssize_t rproc_coredump_write(stru
 	int ret, err = 0;
 	char buf[20];
 
-	if (count > sizeof(buf))
+	if (count < 1 || count > sizeof(buf))
 		return -EINVAL;
 
 	ret = copy_from_user(buf, user_buf, count);