ubi: Fix return value overwrite issue in try_write_vid_and_data()

commit 31a149d5c13c4cbcf97de3435817263a2d8c9d6e upstream.

The commit 2d78aee426d8 ("UBI: simplify LEB write and atomic LEB change code")
adds helper function, try_write_vid_and_data(), to simplify the code, but this
helper function has bug, it will return 0 (success) when ubi_io_write_vid_hdr()
or the ubi_io_write_data() return error number (-EIO, etc), because the return
value of ubi_wl_put_peb() will overwrite the original return value.

This issue will cause unexpected data loss issue, because the caller of this
function and UBIFS willn't know the data is lost.

Fixes: 2d78aee426d8 ("UBI: simplify LEB write and atomic LEB change code")
Cc: stable@vger.kernel.org
Signed-off-by: Wang YanQing <udknight@gmail.com>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index 09c408c45a62186a67cc1efe4bfcd66b258dc49d..4e1d80746b04b26ca3de4715565d2724a7d81db8 100644 (file)
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -946,7 +946,7 @@ static int try_write_vid_and_data(struct ubi_volume *vol, int lnum,
                                  int offset, int len)
 {
        struct ubi_device *ubi = vol->ubi;
-       int pnum, opnum, err, vol_id = vol->vol_id;
+       int pnum, opnum, err, err2, vol_id = vol->vol_id;
 
        pnum = ubi_wl_get_peb(ubi);
        if (pnum < 0) {
@@ -981,10 +981,19 @@ static int try_write_vid_and_data(struct ubi_volume *vol, int lnum,
 out_put:
        up_read(&ubi->fm_eba_sem);
 
-       if (err && pnum >= 0)
-               err = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);
-       else if (!err && opnum >= 0)
-               err = ubi_wl_put_peb(ubi, vol_id, lnum, opnum, 0);
+       if (err && pnum >= 0) {
+               err2 = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);
+               if (err2) {
+                       ubi_warn(ubi, "failed to return physical eraseblock %d, error %d",
+                                pnum, err2);
+               }
+       } else if (!err && opnum >= 0) {
+               err2 = ubi_wl_put_peb(ubi, vol_id, lnum, opnum, 0);
+               if (err2) {
+                       ubi_warn(ubi, "failed to return physical eraseblock %d, error %d",
+                                opnum, err2);
+               }
+       }
 
        return err;
 }