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proc: Avoid mixing integer types in mem_rw()

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[ 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 <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>
This commit is contained in:
Marcelo Henrique Cerri 2021-06-30 18:54:38 -07:00 committed by Greg Kroah-Hartman
parent 76f7eae7ec
commit fc6ac92cfc
1 changed files with 1 additions and 1 deletions
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2
fs/proc/base.c
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@ -855,7 +855,7 @@ 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;