block: initialize integrity buffer to zero before writing it to media

commit 899ee2c3829c5ac14bfc7d3c4a5846c0b709b78f upstream.

Metadata added by bio_integrity_prep is using plain kmalloc, which leads
to random kernel memory being written media.  For PI metadata this is
limited to the app tag that isn't used by kernel generated metadata,
but for non-PI metadata the entire buffer leaks kernel memory.

Fix this by adding the __GFP_ZERO flag to allocations for writes.

Fixes: 7ba1ba12eeef ("block: Block layer data integrity support")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20240613084839.1044015-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Shivani Agarwal <shivani.agarwal@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/block/bio-integrity.c b/block/bio-integrity.c
index a4cfc97275df6ed6b5ee146be5abf4df4c2f8cfd..a5fd04db5ae8e2aec1a5477de74271a5c3f28eb6 100644 (file)
--- a/block/bio-integrity.c
+++ b/block/bio-integrity.c
@@ -216,6 +216,7 @@ bool bio_integrity_prep(struct bio *bio)
        unsigned int bytes, offset, i;
        unsigned int intervals;
        blk_status_t status;
+       gfp_t gfp = GFP_NOIO;
 
        if (!bi)
                return true;
@@ -238,12 +239,20 @@ bool bio_integrity_prep(struct bio *bio)
                if (!bi->profile->generate_fn ||
                    !(bi->flags & BLK_INTEGRITY_GENERATE))
                        return true;
+
+               /*
+                * Zero the memory allocated to not leak uninitialized kernel
+                * memory to disk.  For PI this only affects the app tag, but
+                * for non-integrity metadata it affects the entire metadata
+                * buffer.
+                */
+               gfp |= __GFP_ZERO;
        }
        intervals = bio_integrity_intervals(bi, bio_sectors(bio));
 
        /* Allocate kernel buffer for protection data */
        len = intervals * bi->tuple_size;
-       buf = kmalloc(len, GFP_NOIO | q->bounce_gfp);
+       buf = kmalloc(len, gfp | q->bounce_gfp);
        status = BLK_STS_RESOURCE;
        if (unlikely(buf == NULL)) {
                printk(KERN_ERR "could not allocate integrity buffer\n");