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 <[email protected]> Assisted-by: Claude:claude-opus-4.6 Fixes: 65ff5b7ddf05 ("dm verity: add error handling modes for corrupted blocks") Cc: [email protected] --- drivers/md/dm-verity-target.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6/drivers/md/dm-verity-target.c =================================================================== --- linux-2.6.orig/drivers/md/dm-verity-target.c 2026-07-01 13:31:00.000000000 +0200 +++ linux-2.6/drivers/md/dm-verity-target.c 2026-07-01 18:16:12.000000000 +0200 @@ -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
