From: Nanyong Sun sunnanyong@huawei.com
[ Upstream commit 5f5dec07aca7067216ed4c1342e464e7307a9197 ]
Patch series "nilfs2: fix incorrect usage of kobject".
This patchset from Nanyong Sun fixes memory leak issues and a NULL pointer dereference issue caused by incorrect usage of kboject in nilfs2 sysfs implementation.
This patch (of 6):
Reported by syzkaller:
BUG: memory leak unreferenced object 0xffff888100ca8988 (size 8): comm "syz-executor.1", pid 1930, jiffies 4294745569 (age 18.052s) hex dump (first 8 bytes): 6c 6f 6f 70 31 00 ff ff loop1... backtrace: kstrdup+0x36/0x70 mm/util.c:60 kstrdup_const+0x35/0x60 mm/util.c:83 kvasprintf_const+0xf1/0x180 lib/kasprintf.c:48 kobject_set_name_vargs+0x56/0x150 lib/kobject.c:289 kobject_add_varg lib/kobject.c:384 [inline] kobject_init_and_add+0xc9/0x150 lib/kobject.c:473 nilfs_sysfs_create_device_group+0x150/0x7d0 fs/nilfs2/sysfs.c:986 init_nilfs+0xa21/0xea0 fs/nilfs2/the_nilfs.c:637 nilfs_fill_super fs/nilfs2/super.c:1046 [inline] nilfs_mount+0x7b4/0xe80 fs/nilfs2/super.c:1316 legacy_get_tree+0x105/0x210 fs/fs_context.c:592 vfs_get_tree+0x8e/0x2d0 fs/super.c:1498 do_new_mount fs/namespace.c:2905 [inline] path_mount+0xf9b/0x1990 fs/namespace.c:3235 do_mount+0xea/0x100 fs/namespace.c:3248 __do_sys_mount fs/namespace.c:3456 [inline] __se_sys_mount fs/namespace.c:3433 [inline] __x64_sys_mount+0x14b/0x1f0 fs/namespace.c:3433 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae
If kobject_init_and_add return with error, then the cleanup of kobject is needed because memory may be allocated in kobject_init_and_add without freeing.
And the place of cleanup_dev_kobject should use kobject_put to free the memory associated with the kobject. As the section "Kobject removal" of "Documentation/core-api/kobject.rst" says, kobject_del() just makes the kobject "invisible", but it is not cleaned up. And no more cleanup will do after cleanup_dev_kobject, so kobject_put is needed here.
Link: https://lkml.kernel.org/r/1625651306-10829-1-git-send-email-konishi.ryusuke@... Link: https://lkml.kernel.org/r/1625651306-10829-2-git-send-email-konishi.ryusuke@... Reported-by: Hulk Robot hulkci@huawei.com Link: https://lkml.kernel.org/r/20210629022556.3985106-2-sunnanyong@huawei.com Signed-off-by: Nanyong Sun sunnanyong@huawei.com Signed-off-by: Ryusuke Konishi konishi.ryusuke@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/nilfs2/sysfs.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c index 9c6c0e2e5880..b6a48492fed2 100644 --- a/fs/nilfs2/sysfs.c +++ b/fs/nilfs2/sysfs.c @@ -999,7 +999,7 @@ int nilfs_sysfs_create_device_group(struct super_block *sb) err = kobject_init_and_add(&nilfs->ns_dev_kobj, &nilfs_dev_ktype, NULL, "%s", sb->s_id); if (err) - goto free_dev_subgroups; + goto cleanup_dev_kobject;
err = nilfs_sysfs_create_mounted_snapshots_group(nilfs); if (err) @@ -1036,9 +1036,7 @@ int nilfs_sysfs_create_device_group(struct super_block *sb) nilfs_sysfs_delete_mounted_snapshots_group(nilfs);
cleanup_dev_kobject: - kobject_del(&nilfs->ns_dev_kobj); - -free_dev_subgroups: + kobject_put(&nilfs->ns_dev_kobj); kfree(nilfs->ns_dev_subgroups);
failed_create_device_group: