From: Dan Carpenter dan.carpenter@linaro.org
commit 641db40f3afe7998011bfabc726dba3e698f8196 upstream.
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.
Link: https://lkml.kernel.org/r/b55f7eed-1c65-4adc-95d1-6c7c65a54a6e@moroto.mounta... Fixes: 5d8de293c224 ("vmcore: convert copy_oldmem_page() to take an iov_iter") Signed-off-by: Dan Carpenter dan.carpenter@linaro.org Reviewed-by: Matthew Wilcox (Oracle) willy@infradead.org Acked-by: Baoquan He bhe@redhat.com Cc: Dave Young dyoung@redhat.com Cc: Vivek Goyal vgoyal@redhat.com Cc: Alexey Dobriyan adobriyan@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/proc/vmcore.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -132,7 +132,7 @@ ssize_t read_from_oldmem(struct iov_iter u64 *ppos, bool encrypted) { unsigned long pfn, offset; - size_t nr_bytes; + ssize_t nr_bytes; ssize_t read = 0, tmp; int idx;