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fix: apply boundary check on ldcache parsing #395

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Merged
henry118 merged 1 commit into from
Aug 26, 2026
Merged

fix: apply boundary check on ldcache parsing #395

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16 changes: 16 additions & 0 deletions src/ldcache.c
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,13 @@ ldcache_init(struct ldcache *ctx, struct error *err, const char *path)
*ctx = (struct ldcache){err, path, NULL, NULL, 0};
}

static bool
ldcache_ptr_valid(const struct ldcache *ctx, const void *ptr)
{
return ((const char *)ptr >= (const char *)ctx->addr &&
(const char *)ptr < (const char *)ctx->addr + ctx->size);
}

int
ldcache_open(struct ldcache *ctx)
{
Expand All @@ -77,6 +84,8 @@ ldcache_open(struct ldcache *ctx)
ctx->ptr = h5->libs + h5->nlibs;
padding = (-(uintptr_t)ctx->ptr) & (__alignof__(struct header_libc6) - 1);
ctx->ptr = (char *)ctx->ptr + padding; /* align on header_libc6 boundary */
if (!ldcache_ptr_valid(ctx, ctx->ptr))
goto fail;
}

h6 = (struct header_libc6 *)ctx->ptr;
Expand All @@ -85,6 +94,8 @@ ldcache_open(struct ldcache *ctx)
if (strncmp(h6->magic, MAGIC_LIBC6, MAGIC_LIBC6_LEN) ||
strncmp(h6->version, MAGIC_VERSION, MAGIC_VERSION_LEN))
goto fail;
if (!ldcache_ptr_valid(ctx, h6->libs + h6->nlibs))
goto fail;

return (0);

Expand Down Expand Up @@ -122,6 +133,11 @@ ldcache_resolve(struct ldcache *ctx, uint32_t arch, const char *root, const char
char *key = (char *)ctx->ptr + h->libs[i].key;
char *value = (char *)ctx->ptr + h->libs[i].value;

if (!ldcache_ptr_valid(ctx, key) || !ldcache_ptr_valid(ctx, value)) {
error_setx(ctx->err, "corrupted ldcache entry: %s", ctx->path);
return (-1);
}

if (!(flags & LD_ELF) || (flags & LD_ARCH_MASK) != arch)
continue;

Expand Down
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