From: Marcelo Henrique Cerri marcelo.cerri@canonical.com
[ 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 --- 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 005d4cb2347e..5f68454cf421 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -841,7 +841,7 @@ 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;