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* [nfs-utils PATCH] blkmapd: reject zero-length signature components while decoding block signatures
@ 2026-09-03 17:54 Scott Mayhew
  0 siblings, 0 replies; only message in thread
From: Scott Mayhew @ 2026-09-03 17:54 UTC (permalink / raw)
  To: steved; +Cc: linux-nfs

A zero-length signature can cause blkmapd to map to an unintended
device.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
---
 utils/blkmapd/device-process.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/utils/blkmapd/device-process.c b/utils/blkmapd/device-process.c
index f53a6165..a47cc36e 100644
--- a/utils/blkmapd/device-process.c
+++ b/utils/blkmapd/device-process.c
@@ -81,6 +81,10 @@ static int decode_blk_signature(uint32_t **pp, uint32_t * end,
 		BLK_READBUF(p, end, 12);
 		READ64(comp->bs_offset);
 		READ32(siglen);
+		if (siglen == 0) {
+			BL_LOG_ERR("0 length signature component\n");
+			goto out_err;
+		}
 		comp->bs_length = siglen;
 		BLK_READBUF(p, end, siglen);
 		/* Note we rely here on fact that sig is used immediately
-- 
2.55.0


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