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cli_check_mydoom_log: Avoid unaligned access. #1293

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merged 1 commit into from
Jul 22, 2024
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cli_check_mydoom_log: Avoid unaligned access. #1293

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19 changes: 15 additions & 4 deletions libclamav/special.c
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Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,8 @@

int cli_check_mydoom_log(cli_ctx *ctx)
{
const uint32_t *record;
uint32_t record[16];
const uint32_t *ptr;
uint32_t check, key;
fmap_t *map = ctx->fmap;
unsigned int blocks = map->len / (8 * 4);
Expand All @@ -59,14 +60,24 @@ int cli_check_mydoom_log(cli_ctx *ctx)
if (blocks > 5)
blocks = 5;

record = fmap_need_off_once(map, 0, 8 * 4 * blocks);
if (!record)
/*
* The following pointer might not be properly aligned. There there is
* memcmp() + memcpy() workaround to avoid performing an unaligned access
* while reading the uint32_t.
*/
ptr = fmap_need_off_once(map, 0, 8 * 4 * blocks);
if (!ptr)
return CL_CLEAN;

while (blocks) { /* This wasn't probably intended but that's what the current code does anyway */
if (record[--blocks] == 0xffffffff)
const uint32_t marker_ff = 0xffffffff;

if (!memcmp(&ptr[--blocks], &marker_ff, sizeof(uint32_t)))
return CL_CLEAN;
}

memcpy(record, ptr, sizeof(record));

key = ~be32_to_host(record[0]);
check = (be32_to_host(record[1]) ^ key) +
(be32_to_host(record[2]) ^ key) +
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