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SubjectRe: [PATCH] jfs: fix array-index-out-of-bounds in dbAdjTree
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Just a friendly remainder

On 17/10/23 17:33, Manas Ghandat wrote:
> Currently there is a bound check missing in the dbAdjTree while
> accessing the dmt_stree. To add the required check added the bool is_ctl
> which is required to determine the size as suggest in the following
> commit.
> https://lore.kernel.org/linux-kernel-mentees/f9475918-2186-49b8-b801-6f0f9e75f4fa@oracle.com/
>
> Reported-by: syzbot+39ba34a099ac2e9bd3cb@syzkaller.appspotmail.com
> Fixes: https://syzkaller.appspot.com/bug?extid=39ba34a099ac2e9bd3cb
> Signed-off-by: Manas Ghandat <ghandatmanas@gmail.com>
> ---
> fs/jfs/jfs_dmap.c | 57 ++++++++++++++++++++++++++---------------------
> 1 file changed, 31 insertions(+), 26 deletions(-)
>
> diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
> index 88afd108c2dd..57fba21994c3 100644
> --- a/fs/jfs/jfs_dmap.c
> +++ b/fs/jfs/jfs_dmap.c
> @@ -63,10 +63,10 @@
> */
> static void dbAllocBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
> int nblocks);
> -static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval);
> -static int dbBackSplit(dmtree_t * tp, int leafno);
> -static int dbJoin(dmtree_t * tp, int leafno, int newval);
> -static void dbAdjTree(dmtree_t * tp, int leafno, int newval);
> +static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval, bool is_ctl);
> +static int dbBackSplit(dmtree_t * tp, int leafno, bool is_ctl);
> +static int dbJoin(dmtree_t * tp, int leafno, int newval, bool is_ctl);
> +static void dbAdjTree(dmtree_t * tp, int leafno, int newval, bool is_ctl);
> static int dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc,
> int level);
> static int dbAllocAny(struct bmap * bmp, s64 nblocks, int l2nb, s64 * results);
> @@ -2096,7 +2096,7 @@ static int dbFreeDmap(struct bmap * bmp, struct dmap * dp, s64 blkno,
> * system.
> */
> if (dp->tree.stree[word] == NOFREE)
> - dbBackSplit((dmtree_t *) & dp->tree, word);
> + dbBackSplit((dmtree_t *) & dp->tree, word, false);
>
> dbAllocBits(bmp, dp, blkno, nblocks);
> }
> @@ -2182,7 +2182,7 @@ static void dbAllocBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
> * the binary system of the leaves if need be.
> */
> dbSplit(tp, word, BUDMIN,
> - dbMaxBud((u8 *) & dp->wmap[word]));
> + dbMaxBud((u8 *) & dp->wmap[word]),false);
>
> word += 1;
> } else {
> @@ -2222,7 +2222,7 @@ static void dbAllocBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
> * system of the leaves to reflect the current
> * allocation (size).
> */
> - dbSplit(tp, word, size, NOFREE);
> + dbSplit(tp, word, size, NOFREE, false);
>
> /* get the number of dmap words handled */
> nw = BUDSIZE(size, BUDMIN);
> @@ -2329,7 +2329,7 @@ static int dbFreeBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
> /* update the leaf for this dmap word.
> */
> rc = dbJoin(tp, word,
> - dbMaxBud((u8 *) & dp->wmap[word]));
> + dbMaxBud((u8 *) & dp->wmap[word]),false);
> if (rc)
> return rc;
>
> @@ -2362,7 +2362,7 @@ static int dbFreeBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
>
> /* update the leaf.
> */
> - rc = dbJoin(tp, word, size);
> + rc = dbJoin(tp, word, size, false);
> if (rc)
> return rc;
>
> @@ -2514,16 +2514,16 @@ dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc, int level)
> * that it is at the front of a binary buddy system.
> */
> if (oldval == NOFREE) {
> - rc = dbBackSplit((dmtree_t *) dcp, leafno);
> + rc = dbBackSplit((dmtree_t *) dcp, leafno, true);
> if (rc) {
> release_metapage(mp);
> return rc;
> }
> oldval = dcp->stree[ti];
> }
> - dbSplit((dmtree_t *) dcp, leafno, dcp->budmin, newval);
> + dbSplit((dmtree_t *) dcp, leafno, dcp->budmin, newval, true);
> } else {
> - rc = dbJoin((dmtree_t *) dcp, leafno, newval);
> + rc = dbJoin((dmtree_t *) dcp, leafno, newval, true);
> if (rc) {
> release_metapage(mp);
> return rc;
> @@ -2554,7 +2554,7 @@ dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc, int level)
> */
> if (alloc) {
> dbJoin((dmtree_t *) dcp, leafno,
> - oldval);
> + oldval, true);
> } else {
> /* the dbJoin() above might have
> * caused a larger binary buddy system
> @@ -2564,9 +2564,9 @@ dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc, int level)
> */
> if (dcp->stree[ti] == NOFREE)
> dbBackSplit((dmtree_t *)
> - dcp, leafno);
> + dcp, leafno, true);
> dbSplit((dmtree_t *) dcp, leafno,
> - dcp->budmin, oldval);
> + dcp->budmin, oldval, true);
> }
>
> /* release the buffer and return the error.
> @@ -2614,7 +2614,7 @@ dbAdjCtl(struct bmap * bmp, s64 blkno, int newval, int alloc, int level)
> *
> * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
> */
> -static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval)
> +static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval, bool is_ctl)
> {
> int budsz;
> int cursz;
> @@ -2636,7 +2636,7 @@ static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval)
> while (cursz >= splitsz) {
> /* update the buddy's leaf with its new value.
> */
> - dbAdjTree(tp, leafno ^ budsz, cursz);
> + dbAdjTree(tp, leafno ^ budsz, cursz, is_ctl);
>
> /* on to the next size and buddy.
> */
> @@ -2648,7 +2648,7 @@ static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval)
> /* adjust the dmap tree to reflect the specified leaf's new
> * value.
> */
> - dbAdjTree(tp, leafno, newval);
> + dbAdjTree(tp, leafno, newval, is_ctl);
> }
>
>
> @@ -2679,7 +2679,7 @@ static void dbSplit(dmtree_t * tp, int leafno, int splitsz, int newval)
> *
> * serialization: IREAD_LOCK(ipbmap) or IWRITE_LOCK(ipbmap) held on entry/exit;
> */
> -static int dbBackSplit(dmtree_t * tp, int leafno)
> +static int dbBackSplit(dmtree_t * tp, int leafno, bool is_ctl)
> {
> int budsz, bud, w, bsz, size;
> int cursz;
> @@ -2730,7 +2730,7 @@ static int dbBackSplit(dmtree_t * tp, int leafno)
> * system in two.
> */
> cursz = leaf[bud] - 1;
> - dbSplit(tp, bud, cursz, cursz);
> + dbSplit(tp, bud, cursz, cursz, is_ctl);
> break;
> }
> }
> @@ -2758,7 +2758,7 @@ static int dbBackSplit(dmtree_t * tp, int leafno)
> *
> * RETURN VALUES: none
> */
> -static int dbJoin(dmtree_t * tp, int leafno, int newval)
> +static int dbJoin(dmtree_t * tp, int leafno, int newval, bool is_ctl)
> {
> int budsz, buddy;
> s8 *leaf;
> @@ -2813,12 +2813,12 @@ static int dbJoin(dmtree_t * tp, int leafno, int newval)
> if (leafno < buddy) {
> /* leafno is the left buddy.
> */
> - dbAdjTree(tp, buddy, NOFREE);
> + dbAdjTree(tp, buddy, NOFREE, is_ctl);
> } else {
> /* buddy is the left buddy and becomes
> * leafno.
> */
> - dbAdjTree(tp, leafno, NOFREE);
> + dbAdjTree(tp, leafno, NOFREE, is_ctl);
> leafno = buddy;
> }
>
> @@ -2831,7 +2831,7 @@ static int dbJoin(dmtree_t * tp, int leafno, int newval)
>
> /* update the leaf value.
> */
> - dbAdjTree(tp, leafno, newval);
> + dbAdjTree(tp, leafno, newval, is_ctl);
>
> return 0;
> }
> @@ -2852,15 +2852,20 @@ static int dbJoin(dmtree_t * tp, int leafno, int newval)
> *
> * RETURN VALUES: none
> */
> -static void dbAdjTree(dmtree_t * tp, int leafno, int newval)
> +static void dbAdjTree(dmtree_t * tp, int leafno, int newval, bool is_ctl)
> {
> int lp, pp, k;
> - int max;
> + int max, size;
> +
> + size = is_ctl ? CTLTREESIZE : TREESIZE;
>
> /* pick up the index of the leaf for this leafno.
> */
> lp = leafno + le32_to_cpu(tp->dmt_leafidx);
>
> + if (lp > size || lp < 0)
> + return;
> +
> /* is the current value the same as the old value ? if so,
> * there is nothing to do.
> */

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