From: Marcelo Henrique Cerri <marcelo.cerri@xxxxxxxxxxxxx> Subject: 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/20210512125215.3348316-1-marcelo.cerri@xxxxxxxxxxxxx Reviewed-by: David Disseldorp <ddiss@xxxxxxx> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxxxxx> Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@xxxxxxxxxxxxx> Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx> Cc: Souza Cascardo <cascardo@xxxxxxxxxxxxx> Cc: Christian Brauner <christian.brauner@xxxxxxxxxx> Cc: Michel Lespinasse <walken@xxxxxxxxxx> Cc: Helge Deller <deller@xxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/base.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/proc/base.c~proc-avoid-mixing-integer-types-in-mem_rw +++ a/fs/proc/base.c @@ -854,7 +854,7 @@ static ssize_t mem_rw(struct file *file, 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; _
