From e3aa8da5dd34af860cc9419f5a159107823f53aa Mon Sep 17 00:00:00 2001 From: Baokun Li Date: Tue, 16 Jul 2024 17:29:29 +0800 Subject: [PATCH] ext4: avoid ptr null pointer dereference BugLink: https://bugs.launchpad.net/bugs/2078289 When commit 13df4d44a3aa ("ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists()") was backported to stable, the commit f536808adcc3 ("ext4: refactor out ext4_generic_attr_store()") that uniformly determines if the ptr is null is not merged in, so it needs to be judged whether ptr is null or not in each case of the switch, otherwise null pointer dereferencing may occur. Fixes: 677ff4589f15 ("ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists()") Signed-off-by: Baokun Li Signed-off-by: Greg Kroah-Hartman Signed-off-by: Portia Stephens Signed-off-by: Stefan Bader --- fs/ext4/sysfs.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c index 63cbda3700ea..d65dccb44ed5 100644 --- a/fs/ext4/sysfs.c +++ b/fs/ext4/sysfs.c @@ -473,6 +473,8 @@ static ssize_t ext4_attr_store(struct kobject *kobj, *((unsigned int *) ptr) = t; return len; case attr_clusters_in_group: + if (!ptr) + return 0; ret = kstrtouint(skip_spaces(buf), 0, &t); if (ret) return ret;