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parser_lyb: fix integer overflow and OOM in lyb_read_string/lyb_read_value #2513

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Merged
michalvasko merged 1 commit into from
May 6, 2026
+8 −0
Merged

parser_lyb: fix integer overflow and OOM in lyb_read_string/lyb_read_value #2513

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8 changes: 8 additions & 0 deletions src/parser_lyb.c
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Original file line number Diff line number Diff line change
Expand Up @@ -284,6 +284,9 @@ lyb_read_string(char **str, struct lylyb_parse_ctx *lybctx)
/* read length in bytes */
lyb_read_size(&str_len, lybctx);

/* str_len + 1 wraps to 0 when str_len == UINT32_MAX, causing malloc(0) followed by an out-of-bounds write */
LY_CHECK_ERR_RET(str_len == UINT32_MAX, LOGERR(lybctx->ctx, LY_EINVAL, "LYB string length overflow."), LY_EINVAL);

/* allocate mem */
*str = malloc((str_len + 1) * sizeof **str);
LY_CHECK_ERR_RET(!*str, LOGMEM(lybctx->ctx), LY_EMEM);
Expand Down Expand Up @@ -340,6 +343,11 @@ lyb_read_value(const struct lysc_type *type, uint8_t **val, uint64_t *val_size_b
}
}

/* LYPLG_BITS2BYTES(val_size_bits) + 1 can reach 4 GiB when lyb_size_bits == UINT32_MAX and
* size_type == VARIABLE_BYTES, causing calloc to attempt a 4 GiB allocation (OOM / DoS) */
LY_CHECK_ERR_RET(LYPLG_BITS2BYTES(*val_size_bits) >= UINT32_MAX,
LOGERR(lybctx->ctx, LY_EINVAL, "LYB value size overflow."), LY_EINVAL);

/* allocate zeroed memory with an addition zero byte */
*val = calloc(LYPLG_BITS2BYTES(*val_size_bits) + 1, sizeof **val);
LY_CHECK_ERR_RET(!*val, LOGMEM(lybctx->ctx), LY_EMEM);
Expand Down
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