proc: Avoid mixing integer types in mem_rw()

Use size_t when capping the count argument received by mem_rw(). Since
count is size_t, using min_t(int, ...) can lead to a negative value
that will later be passed to access_remote_vm(), which can cause
unexpected behavior.

Since we are capping the value to at maximum PAGE_SIZE, the conversion
from size_t to int when passing it to access_remote_vm() as "len"
shouldn't be a problem.

Link: https://lkml.kernel.org/r/[email protected]
Reviewed-by: David Disseldorp <[email protected]>
Signed-off-by: Thadeu Lima de Souza Cascardo <[email protected]>
Signed-off-by: Marcelo Henrique Cerri <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: Souza Cascardo <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Michel Lespinasse <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 9cbd915025ad..a0a2fc1c9da2 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -854,7 +854,7 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
 	flags = FOLL_FORCE | (write ? FOLL_WRITE : 0);
 
 	while (count > 0) {
-		int this_len = min_t(int, count, PAGE_SIZE);
+		size_t this_len = min_t(size_t, count, PAGE_SIZE);
 
 		if (write && copy_from_user(page, buf, this_len)) {
 			copied = -EFAULT;