From 08c281304cd6fd7bf20f5eb7aaa81c7ee4283b0c Mon Sep 17 00:00:00 2001 From: TristanInSec Date: Mon, 18 May 2026 13:30:02 -0400 Subject: [PATCH] dissect: guard against ssize_t overflow in LUKS2 header parser The json_len variable is ssize_t, but the subtraction be64toh(header.hdr_len) - LUKS2_FIXED_HDR_SIZE can yield a value exceeding SSIZE_MAX when hdr_len is a large crafted value. This causes signed integer overflow and a subsequent oversized malloc() that fails with -ENOMEM, producing a misleading out-of-memory error. Add an explicit check against SSIZE_MAX before the cast to ssize_t. --- src/shared/dissect-image.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/src/shared/dissect-image.c b/src/shared/dissect-image.c index c5bb52b2af..3aeb254fd4 100644 --- a/src/shared/dissect-image.c +++ b/src/shared/dissect-image.c @@ -446,6 +446,9 @@ static int partition_is_luks2_integrity(int part_fd, uint64_t offset, uint64_t s if (be64toh(header.hdr_len) <= LUKS2_FIXED_HDR_SIZE || offset > UINT64_MAX - be64toh(header.hdr_len)) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Invalid LUKS header length: %" PRIu64 ".", be64toh(header.hdr_len)); + if (be64toh(header.hdr_len) - LUKS2_FIXED_HDR_SIZE > (uint64_t) SSIZE_MAX) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "LUKS header JSON area too large: %" PRIu64 ".", be64toh(header.hdr_len)); + json_len = be64toh(header.hdr_len) - LUKS2_FIXED_HDR_SIZE; json = malloc(json_len + 1); if (!json)