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[01/12] block: initialize integrity buffer to zero before writing it to media

Message ID 20240613084839.1044015-2-hch@lst.de
State New
Headers show
Series [01/12] block: initialize integrity buffer to zero before writing it to media | expand

Commit Message

Christoph Hellwig June 13, 2024, 8:48 a.m. UTC 
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>
---
 block/bio-integrity.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

Comments

Martin K. Petersen June 14, 2024, 2:02 a.m. UTC | #1 
Christoph,

> 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.

Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Kanchan Joshi June 14, 2024, 12:45 p.m. UTC | #2 
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
diff mbox series

Patch

diff --git a/block/bio-integrity.c b/block/bio-integrity.c
index 2e3e8e04961eae..af7f71d16114de 100644
--- a/block/bio-integrity.c
+++ b/block/bio-integrity.c
@@ -432,6 +432,7 @@  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;
@@ -454,11 +455,19 @@  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;