ubi: ubi_wl_put_peb: Fix infinite loop when wear-leveling work failed

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ubi: ubi_wl_put_peb: Fix infinite loop when wear-leveling work failed Following process will trigger an infinite loop in ubi_wl_put_peb(): ubifs_bgt ubi_bgt ubifs_leb_unmap ubi_leb_unmap ubi_eba_unmap_leb ubi_wl_put_peb wear_leveling_worker e1 = rb_entry(rb_first(&ubi->used) e2 = get_peb_for_wl(ubi) ubi_io_read_vid_hdr // return err (flash fault) out_error: ubi->move_from = ubi->move_to = NULL wl_entry_destroy(ubi, e1) ubi->lookuptbl[e->pnum] = NULL retry: e = ubi->lookuptbl[pnum]; // return NULL if (e == ubi->move_from) { // NULL == NULL gets true goto retry; // infinite loop !!! $ top PID USER PR NI VIRT RES SHR S %CPU %MEM COMMAND 7676 root 20 0 0 0 0 R 100.0 0.0 ubifs_bgt0_0 Fix it by: 1) Letting ubi_wl_put_peb() returns directly if wearl leveling entry has been removed from 'ubi->lookuptbl'. 2) Using 'ubi->wl_lock' protecting wl entry deletion to preventing an use-after-free problem for wl entry in ubi_wl_put_peb(). Fetch a reproducer in [Link].

References

• https://git.kernel.org/stable/c/b40d2fbf47af58377e898b5062077a47bb28a132
• https://git.kernel.org/stable/c/f006f596fe851c3b6aae60b79f89f89f0e515d2f
• https://git.kernel.org/stable/c/b5be23f6ae610bdb262160a1f294afee6d0e6a69
• https://git.kernel.org/stable/c/8a18856e074479bd050b01e688c58defadce7ab0
• https://git.kernel.org/stable/c/3afaaf6f5867dc4ad383808d4053f428ec7b867d
• https://git.kernel.org/stable/c/cc4bc532acda66189bddc03b3fe1ad689d9a48a2
• https://git.kernel.org/stable/c/5af1c643184a5d09ff5b3f334077a4d0a163c677
• https://git.kernel.org/stable/c/4d57a7333e26040f2b583983e1970d9d460e56b0