The patch titled
Subject: proc/vmcore: fix signedness bug in read_from_oldmem()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
proc-vmcore-fix-signedness-bug-in-read_from_oldmem.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/proc-vmcore-fix-signedness-bug-in-read_from_oldmem.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Subject: proc/vmcore: fix signedness bug in read_from_oldmem()
Date: Tue, 25 Jul 2023 20:03:16 +0300
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.mountain
Fixes: 5d8de293c224 ("vmcore: convert copy_oldmem_page() to take an iov_iter")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Acked-by: Baoquan He <bhe@xxxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/vmcore.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/proc/vmcore.c~proc-vmcore-fix-signedness-bug-in-read_from_oldmem
+++ a/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;
_
Patches currently in -mm which might be from dan.carpenter@xxxxxxxxxx are
proc-vmcore-fix-signedness-bug-in-read_from_oldmem.patch
