dm-verity: increase sprintf buffer size

The prefix "DM_VERITY_ERR_BLOCK_NR" is 22 chars. Add '=', one digit for
type, ',', up to 20 digits for a u64 block number, and a NUL terminator:
that's 46 bytes. The buffer is 42 bytes. For block numbers >= 16 decimal
digits (devices larger than ~16 EB with 4K blocks), snprintf silently
truncates the uevent environment variable.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Assisted-by: Claude:claude-opus-4.6
Fixes: 65ff5b7ddf05 ("dm verity: add error handling modes for corrupted blocks")
Cc: stable@vger.kernel.org

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index adfda1fdab6aa5ac22a4ffb38d78008945186d46..e63a8290bd3af4b0061cc82e12ad646fb3e9d595 100644 (file)
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -26,7 +26,7 @@
 
 #define DM_MSG_PREFIX                  "verity"
 
-#define DM_VERITY_ENV_LENGTH           42
+#define DM_VERITY_ENV_LENGTH           46
 #define DM_VERITY_ENV_VAR_NAME         "DM_VERITY_ERR_BLOCK_NR"
 
 #define DM_VERITY_DEFAULT_PREFETCH_SIZE        262144