The bug is the error handling:
if (tmp < nr_bytes) {
"tmp" can hold negative error codes but because "nr_bytes" is type
size_t the negative error codes are treated as very high positive
values (success). Fix this by changing "nr_bytes" to type ssize_t. The
"nr_bytes" variable is used to store values between 1 and PAGE_SIZE and
they can fit in ssize_t without any issue.
Fixes: 5d8de293c224 ("vmcore: convert copy_oldmem_page() to take an iov_iter")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
fs/proc/vmcore.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index cb80a7703d58..1fb213f379a5 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -132,7 +132,7 @@ ssize_t read_from_oldmem(struct iov_iter *iter, size_t count,
u64 *ppos, bool encrypted)
{
unsigned long pfn, offset;
- size_t nr_bytes;
+ ssize_t nr_bytes;
ssize_t read = 0, tmp;
int idx;
--
2.39.2
