From: Marcelo Henrique Cerri <marcelo.cerri@canonical.com> stable inclusion from linux-4.19.199 commit 66bcd449e04c2530d9859ff628d2596658bcf825 -------------------------------- [ 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.c... Reviewed-by: David Disseldorp <ddiss@suse.de> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Souza Cascardo <cascardo@canonical.com> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Michel Lespinasse <walken@google.com> Cc: Helge Deller <deller@gmx.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- 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 a8679c244e40a..24fb694357338 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -835,7 +835,7 @@ 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; -- 2.25.1