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[delta] Add bounds checks for delta image #693

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Merged
dgarske merged 4 commits into from
Feb 24, 2026
Merged

[delta] Add bounds checks for delta image #693

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96228bd
Added boundary checks for delta image
danielinux Feb 24, 2026
b180574
Addressed copilot's comments
danielinux Feb 24, 2026
a4dc9c3
Use partition size as bound if header sector is erased
danielinux Feb 24, 2026
c9d94d6
Using 'len' iso magic number 70000 in test
danielinux Feb 24, 2026
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17 changes: 12 additions & 5 deletions src/delta.c
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Original file line number Diff line number Diff line change
Expand Up @@ -106,6 +106,7 @@ int wb_patch(WB_PATCH_CTX *ctx, uint8_t *dst, uint32_t len)
uint32_t src_off;
uint16_t sz;
uint32_t copy_sz;
uint32_t resume_sz;
if (!ctx)
return -1;
if (len < BLOCK_HDR_SIZE)
Expand All @@ -115,10 +116,13 @@ int wb_patch(WB_PATCH_CTX *ctx, uint8_t *dst, uint32_t len)
uint8_t *pp = patch_read_cache(ctx);
if (ctx->matching) {
/* Resume matching block from previous sector */
sz = ctx->blk_sz;
if (sz > len)
sz = len;
memcpy(dst + dst_off, ctx->src_base + ctx->blk_off, sz);
resume_sz = ctx->blk_sz;
if (resume_sz > len)
resume_sz = len;
if (ctx->blk_off > ctx->src_size ||
resume_sz > ctx->src_size - ctx->blk_off)
return -1;
memcpy(dst + dst_off, ctx->src_base + ctx->blk_off, resume_sz);
if (ctx->blk_sz > len) {
ctx->blk_sz -= len;
ctx->blk_off += len;
Expand All @@ -127,7 +131,7 @@ int wb_patch(WB_PATCH_CTX *ctx, uint8_t *dst, uint32_t len)
ctx->blk_sz = 0;
ctx->matching = 0;
}
dst_off += sz;
dst_off += resume_sz;
continue;
}
if (*pp == ESC) {
Expand All @@ -142,6 +146,9 @@ int wb_patch(WB_PATCH_CTX *ctx, uint8_t *dst, uint32_t len)
src_off = (hdr->off[0] << 16) + (hdr->off[1] << 8) +
hdr->off[2];
sz = (hdr->sz[0] << 8) + hdr->sz[1];
if (src_off > ctx->src_size ||
sz > ctx->src_size - src_off)
return -1;
ctx->matching = 1;
if (sz > (len - dst_off)) {
copy_sz = len - dst_off;
Expand Down
5 changes: 5 additions & 0 deletions src/update_flash.c
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Original file line number Diff line number Diff line change
Expand Up @@ -441,6 +441,11 @@ static int wolfBoot_delta_update(struct wolfBoot_image *boot,
uint16_t base_hash_sz;
uint8_t *base_hash;

if (boot->fw_size == 0) {
/* Resume after powerfail can leave boot header erased; bound by partition size. */
boot->fw_size = WOLFBOOT_PARTITION_SIZE - IMAGE_HEADER_SIZE;
}

/* Use biggest size for the swap */
total_size = boot->fw_size + IMAGE_HEADER_SIZE;
if ((update->fw_size + IMAGE_HEADER_SIZE) > total_size)
Expand Down
68 changes: 68 additions & 0 deletions tools/unit-tests/unit-delta.c
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,71 @@ START_TEST(test_wb_patch_init_invalid)
}
END_TEST

START_TEST(test_wb_patch_src_bounds_invalid)
{
WB_PATCH_CTX patch_ctx;
uint8_t src[SRC_SIZE] = {0};
uint8_t patch[PATCH_SIZE] = {0};
uint8_t dst[DELTA_BLOCK_SIZE] = {0};
int ret;

/* ESC + header with src_off beyond src_size */
patch[0] = ESC;
patch[1] = 0x00; /* off[0] */
patch[2] = 0x10; /* off[1] -> 0x0010FF */
patch[3] = 0xFF; /* off[2] */
patch[4] = 0x00; /* sz[0] */
patch[5] = 0x10; /* sz[1] -> 16 */

ret = wb_patch_init(&patch_ctx, src, SRC_SIZE, patch, BLOCK_HDR_SIZE);
ck_assert_int_eq(ret, 0);

ret = wb_patch(&patch_ctx, dst, sizeof(dst));
ck_assert_int_eq(ret, -1);
}
END_TEST

START_TEST(test_wb_patch_resume_bounds_invalid)
{
WB_PATCH_CTX patch_ctx;
uint8_t src[SRC_SIZE] = {0};
uint8_t patch[PATCH_SIZE] = {0};
uint8_t dst[DELTA_BLOCK_SIZE] = {0};
int ret;

ret = wb_patch_init(&patch_ctx, src, SRC_SIZE, patch, BLOCK_HDR_SIZE);
ck_assert_int_eq(ret, 0);

patch_ctx.matching = 1;
patch_ctx.blk_off = SRC_SIZE + 1;
patch_ctx.blk_sz = 4;

ret = wb_patch(&patch_ctx, dst, sizeof(dst));
ck_assert_int_eq(ret, -1);
}
END_TEST

START_TEST(test_wb_patch_resume_large_len)
{
WB_PATCH_CTX patch_ctx;
uint8_t src[SRC_SIZE] = {0};
uint8_t patch[PATCH_SIZE] = {0};
uint8_t dst[DST_SIZE] = {0};
uint32_t len = 70000;
int ret;

src[0] = 0xA5;
ret = wb_patch_init(&patch_ctx, src, SRC_SIZE, patch, BLOCK_HDR_SIZE);
ck_assert_int_eq(ret, 0);

patch_ctx.matching = 1;
patch_ctx.blk_off = 0;
patch_ctx.blk_sz = len;

ret = wb_patch(&patch_ctx, dst, len);
ck_assert_int_eq(ret, -1);
}
END_TEST

START_TEST(test_wb_diff_init_invalid)
{
Expand Down Expand Up @@ -162,6 +227,9 @@ Suite *patch_diff_suite(void)

tcase_add_test(tc_wolfboot_delta, test_wb_patch_init_invalid);
tcase_add_test(tc_wolfboot_delta, test_wb_diff_init_invalid);
tcase_add_test(tc_wolfboot_delta, test_wb_patch_src_bounds_invalid);
tcase_add_test(tc_wolfboot_delta, test_wb_patch_resume_bounds_invalid);
tcase_add_test(tc_wolfboot_delta, test_wb_patch_resume_large_len);
tcase_add_test(tc_wolfboot_delta, test_wb_patch_and_diff);
suite_add_tcase(s, tc_wolfboot_delta);

Expand Down