kernel.git/drivers/mtd/ubi/eba.c, branch linux-4.4.y

ubi: Fix races around ubi_refill_pools()

2018-07-25T08:18:33Z

commit 2e8f08deabbc7eefe4c5838aaa6aa9a23a8acf2e upstream. When writing a new Fastmap the first thing that happens is refilling the pools in memory. At this stage it is possible that new PEBs from the new pools get already claimed and written with data. If this happens before the new Fastmap data structure hits the flash and we face power cut the freshly written PEB will not scanned and unnoticed. Solve the issue by locking the pools until Fastmap is written. Cc: Fixes: dbb7d2a88d ("UBI: Add fastmap core") Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

ubi: fastmap: Correctly handle interrupted erasures in EBA

2018-07-11T14:03:47Z

commit 781932375ffc6411713ee0926ccae8596ed0261c upstream. Fastmap cannot track the LEB unmap operation, therefore it can happen that after an interrupted erasure the mapping still looks good from Fastmap's point of view, while reading from the PEB will cause an ECC error and confuses the upper layer. Instead of teaching users of UBI how to deal with that, we read back the VID header and check for errors. If the PEB is empty or shows ECC errors we fixup the mapping and schedule the PEB for erasure. Fixes: dbb7d2a88d2a ("UBI: Add fastmap core") Cc: Reported-by: martin bayern Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

ubi: Make recover_peb power cut aware

2016-07-27T16:47:33Z

commit 972228d87445dc46c0a01f5f3de673ac017626f7 upstream. recover_peb() was never power cut aware, if a power cut happened right after writing the VID header upon next attach UBI would blindly use the new partial written PEB and all data from the old PEB is lost. In order to make recover_peb() power cut aware, write the new VID with a proper crc and copy_flag set such that the UBI attach process will detect whether the new PEB is completely written or not. We cannot directly use ubi_eba_atomic_leb_change() since we'd have to unlock the LEB which is facing a write error. Reported-by: Jörg Pfähler Reviewed-by: Jörg Pfähler Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

UBI: Fix static volume checks when Fastmap is used

2016-06-01T19:15:54Z

commit 1900149c835ab5b48bea31a823ea5e5a401fb560 upstream. Ezequiel reported that he's facing UBI going into read-only mode after power cut. It turned out that this behavior happens only when updating a static volume is interrupted and Fastmap is used. A possible trace can look like: ubi0 warning: ubi_io_read_vid_hdr [ubi]: no VID header found at PEB 2323, only 0xFF bytes ubi0 warning: ubi_eba_read_leb [ubi]: switch to read-only mode CPU: 0 PID: 833 Comm: ubiupdatevol Not tainted 4.6.0-rc2-ARCH #4 Hardware name: SAMSUNG ELECTRONICS CO., LTD. 300E4C/300E5C/300E7C/NP300E5C-AD8AR, BIOS P04RAP 10/15/2012 0000000000000286 00000000eba949bd ffff8800c45a7b38 ffffffff8140d841 ffff8801964be000 ffff88018eaa4800 ffff8800c45a7bb8 ffffffffa003abf6 ffffffff850e2ac0 8000000000000163 ffff8801850e2ac0 ffff8801850e2ac0 Call Trace: [] dump_stack+0x63/0x82 [] ubi_eba_read_leb+0x486/0x4a0 [ubi] [] ubi_check_volume+0x83/0xf0 [ubi] [] ubi_open_volume+0x177/0x350 [ubi] [] vol_cdev_open+0x58/0xb0 [ubi] [] chrdev_open+0xae/0x1d0 [] do_dentry_open+0x1ff/0x300 [] ? cdev_put+0x30/0x30 [] vfs_open+0x56/0x60 [] path_openat+0x4f4/0x1190 [] do_filp_open+0x91/0x100 [] ? __alloc_fd+0xc7/0x190 [] do_sys_open+0x13f/0x210 [] SyS_open+0x1e/0x20 [] entry_SYSCALL_64_fastpath+0x1a/0xa4 UBI checks static volumes for data consistency and reads the whole volume upon first open. If the volume is found erroneous users of UBI cannot read from it, but another volume update is possible to fix it. The check is performed by running ubi_eba_read_leb() on every allocated LEB of the volume. For static volumes ubi_eba_read_leb() computes the checksum of all data stored in a LEB. To verify the computed checksum it has to read the LEB's volume header which stores the original checksum. If the volume header is not found UBI treats this as fatal internal error and switches to RO mode. If the UBI device was attached via a full scan the assumption is correct, the volume header has to be present as it had to be there while scanning to get known as mapped. If the attach operation happened via Fastmap the assumption is no longer correct. When attaching via Fastmap UBI learns the mapping table from Fastmap's snapshot of the system state and not via a full scan. It can happen that a LEB got unmapped after a Fastmap was written to the flash. Then UBI can learn the LEB still as mapped and accessing it returns only 0xFF bytes. As UBI is not a FTL it is allowed to have mappings to empty PEBs, it assumes that the layer above takes care of LEB accounting and referencing. UBIFS does so using the LEB property tree (LPT). For static volumes UBI blindly assumes that all LEBs are present and therefore special actions have to be taken. The described situation can happen when updating a static volume is interrupted, either by a user or a power cut. The volume update code first unmaps all LEBs of a volume and then writes LEB by LEB. If the sequence of operations is interrupted UBI detects this either by the absence of LEBs, no volume header present at scan time, or corrupted payload, detected via checksum. In the Fastmap case the former method won't trigger as no scan happened and UBI automatically thinks all LEBs are present. Only by reading data from a LEB it detects that the volume header is missing and incorrectly treats this as fatal error. To deal with the situation ubi_eba_read_leb() from now on checks whether we attached via Fastmap and handles the absence of a volume header like a data corruption error. This way interrupted static volume updates will correctly get detected also when Fastmap is used. Reported-by: Ezequiel Garcia Tested-by: Ezequiel Garcia Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

UBI: Fix debug message

2015-10-03T18:09:55Z

We have to use j instead of i. i is the volume id and not the block. Reported-by: Alexander.Block@continental-corporation.com Signed-off-by: Richard Weinberger Acked-by: Brian Norris

UBI: Fastmap: Locking updates

2015-03-26T21:46:02Z

a) Rename ubi->fm_sem to ubi->fm_eba_sem as this semaphore protects EBA changes. b) Turn ubi->fm_mutex into a rw semaphore. It will still serialize fastmap writes but also ensures that ubi_wl_put_peb() is not interrupted by a fastmap write. We use a rw semaphore to allow ubi_wl_put_peb() still to be executed in parallel if no fastmap write is happening. Signed-off-by: Richard Weinberger

UBI: Fastmap: Fix race after ubi_wl_get_peb()

2015-03-26T21:46:01Z

ubi_wl_get_peb() returns a fresh PEB which can be used by user of UBI. Due to the pool logic fastmap will correctly map this PEB upon attach time because it will be scanned. If a new fastmap is written (due to heavy parallel io) while the before the fresh PEB is assigned to the EBA table it will not be scanned as it is no longer in the pool. So, the race window exists between ubi_wl_get_peb() and the EBA table assignment. We have to make sure that no new fastmap can be written while that. To ensure that ubi_wl_get_peb() will grab ubi->fm_sem in read mode and the user of ubi_wl_get_peb() has to release it after the PEB got assigned. Signed-off-by: Richard Weinberger

UBI: Fastmap: Fix race in ubi_eba_atomic_leb_change()

2015-03-26T21:45:58Z

This function a) requests a new PEB, b) writes data to it, c) returns the old PEB and d) registers the new PEB in the EBA table. For the non-fastmap case this works perfectly fine and is powercut safe. Is fastmap enabled this can lead to issues. If a new fastmap is written between a) and c) the freshly requested PEB is no longer in a pool and will not be scanned upon attaching. If now a powercut happens between c) and d) the freshly requested PEB will not be scanned and the old one got already scheduled for erase. After attaching the EBA table will point to a erased PEB. Fix this issue by swapping steps c) and d). Signed-off-by: Richard Weinberger

UBI: fix out of bounds write

2015-03-26T11:07:17Z

If aeb->len >= vol->reserved_pebs, we should not be writing aeb into the PEB->LEB mapping. Caught by Coverity, CID #711212. Cc: stable Signed-off-by: Brian Norris Signed-off-by: Richard Weinberger

UBI: fix missing brace control flow

2015-02-23T21:17:24Z

commit 0e707ae79ba3 ("UBI: do propagate positive error codes up") seems to have produced an unintended change in the control flow here. Completely untested, but it looks obvious. Caught by Coverity, which didn't like the indentation. CID 1271184. Signed-off-by: Brian Norris Cc: Dan Carpenter Signed-off-by: Richard Weinberger