[PATCH] bcachefs: fix uninitialised-access bug in bch2_alloc_sectors_start_trans

[Qasim Ijaz]

During bch2_alloc_sectors_start_trans() if bch2_trans_relock() fails
the code jumps to label "err", skipping "cl" initialisation. Once at
the "err" label "cl" could potentially be accessed leading to a uinit
access.

Fix this by moving "cl" initialisation before bch2_trans_relock().

Fixes: c2e7fa88544d ("bcachefs: Use a loop for open_bucket_add_buckets() 
retries")
Signed-off-by: Qasim Ijaz <qasde...@gmail.com>
---
 fs/bcachefs/alloc_foreground.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/bcachefs/alloc_foreground.c b/fs/bcachefs/alloc_foreground.c
index 1410a4afb36a..ccd51bcbcec5 100644
--- a/fs/bcachefs/alloc_foreground.c
+++ b/fs/bcachefs/alloc_foreground.c
@@ -1277,6 +1277,11 @@ int bch2_alloc_sectors_start_trans(struct btree_trans 
*trans,
 
        req->data_type          = req->wp->data_type;
 
+       /* If we're going to fall back to the whole fs, try nonblocking first */
+       struct closure *cl = req->target && !(flags & 
BCH_WRITE_only_specified_devs)
+               ? _cl
+               : NULL;
+
        ret = bch2_trans_relock(trans);
        if (ret)
                goto err;
@@ -1285,10 +1290,6 @@ int bch2_alloc_sectors_start_trans(struct btree_trans 
*trans,
        if (req->data_type != BCH_DATA_user)
                req->have_cache = true;
 
-       /* If we're going to fall back to the whole fs, try nonblocking first */
-       struct closure *cl = req->target && !(flags & 
BCH_WRITE_only_specified_devs)
-               ? _cl
-               : NULL;
        while (1) {
                ret = open_bucket_add_buckets(trans, req, cl);
                if (!ret ||
-- 
2.39.5