[PATCH 01/39] memcg_write_event_control(): fix a user-triggerable oops

viro
2024-07-30T05:14:47Z

From: Al Viro <viro@zeniv.linux.org.uk>

we are *not* guaranteed that anything past the terminating NUL
is mapped (let alone initialized with anything sane).

[the sucker got moved in mainline]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
mm/memcontrol-v1.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
index 2aeea4d8bf8e..417c96f2da28 100644
--- a/mm/memcontrol-v1.c
+++ b/mm/memcontrol-v1.c
@@ -1842,9 +1842,12 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
buf = endp + 1;

cfd = simple_strtoul(buf, &endp, 10);
- if ((*endp != ' ') && (*endp != '\0'))
+ if (*endp == '\0')
+ buf = endp;
+ else if (*endp == ' ')
+ buf = endp + 1;
+ else
return -EINVAL;
- buf = endp + 1;

event = kzalloc(sizeof(*event), GFP_KERNEL);
if (!event)
--
2.39.2