From 947644647b3e6b3e6a7db2b71f3ecc598ace27b5 Mon Sep 17 00:00:00 2001 From: Marcelo Henrique Cerri Date: Wed, 30 Jun 2021 18:54:38 -0700 Subject: [PATCH] proc: Avoid mixing integer types in mem_rw() [ Upstream commit d238692b4b9f2c36e35af4c6e6f6da36184aeb3e ] 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/20210512125215.3348316-1-marcelo.cerri@canonical.com Reviewed-by: David Disseldorp Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Marcelo Henrique Cerri Cc: Alexey Dobriyan Cc: Souza Cascardo Cc: Christian Brauner Cc: Michel Lespinasse Cc: Helge Deller Cc: Oleg Nesterov Cc: Lorenzo Stoakes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- fs/proc/base.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 0368ff9335cb..886e408f4769 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -867,7 +867,7 @@ static ssize_t mem_rw(struct file *file, char __user *buf, flags |= FOLL_WRITE; 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;