releases/6.10.3/block-initialize-integrity-buffer-to-zero-before-wri.patch

From f4facc2b0739976a0adcb4e5c740653f7125fb0d Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Thu, 13 Jun 2024 10:48:11 +0200
Subject: block: initialize integrity buffer to zero before writing it to media

From: Christoph Hellwig <hch@lst.de>

[ Upstream commit 899ee2c3829c5ac14bfc7d3c4a5846c0b709b78f ]

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: Sasha Levin <sashal@kernel.org>
---
 block/bio-integrity.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/block/bio-integrity.c b/block/bio-integrity.c
index 8b528e12136f5..741581a752c47 100644
--- a/block/bio-integrity.c
+++ b/block/bio-integrity.c
@@ -454,6 +454,7 @@ bool bio_integrity_prep(struct bio *bio)
 	unsigned long start, end;
 	unsigned int len, nr_pages;
 	unsigned int bytes, offset, i;
+	gfp_t gfp = GFP_NOIO;
 
 	if (!bi)
 		return true;
@@ -476,11 +477,19 @@ 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;
 	}
 
 	/* Allocate kernel buffer for protection data */
 	len = bio_integrity_bytes(bi, bio_sectors(bio));
-	buf = kmalloc(len, GFP_NOIO);
+	buf = kmalloc(len, gfp);
 	if (unlikely(buf == NULL)) {
 		printk(KERN_ERR "could not allocate integrity buffer\n");
 		goto err_end_io;
-- 
2.43.0