Hi Dan,
On 07/25/23 at 08:03pm, Dan Carpenter wrote:
> 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;
Thanks for this fix. Just curious, this is found out by code exploring,
or any breaking?
Acked-by: Baoquan He <bhe@xxxxxxxxxx>
