On 2019-09-09 15:47, rishabhb@xxxxxxxxxxxxxx wrote:
Hi Miklos In 4.19 kernel when we write to a file that doesn't exist we see the following stack: [ 377.382745] ovl_create_or_link+0xac/0x710 [ 377.382745] ovl_create_object+0xb8/0x110 [ 377.382745] ovl_create+0x34/0x40 [ 377.382745] path_openat+0xd44/0x15a8 [ 377.382745] do_filp_open+0x80/0x128 [ 377.382745] do_sys_open+0x140/0x250 [ 377.382745] __arm64_sys_openat+0x2c/0x38 If the override_cred flag = off, the ovl_override_cred and ovl_revert_cred just returns NULL. But there is another override_cred in between these two functions; put_cred(override_creds(override_cred)); put_cred(override_cred); This will override the credentials permanently as there is no corresponding revert_cred associated. So whenever we do commit_creds for this task, we see a BUG_ON at kernel/cred.c +443. https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/cred.c#n443 Should this override_cred be changed to ovl_override_cred to maintain consistency and avoid this BUG_ON? Thanks, Rishabh
Corrected line number in the subject.
