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Prevent potential uninitialized memory access

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Before this change, cf_OpenLibrary() did something along the lines of
this:

  char id[4];
  fread(id, 4, 1, fp);
  strncmp(id, "HOG2", 4);

If fread() finishes successfully, then that code is fine. However,
fread() might encounter an error or bump into the end of a file. In
those scenarios, the value of id will not necessarily be initialized
[1]. In other words, when fread() fails, strncmp() might operate on
uninitialized memory.

This change makes sure that the value of id only gets used if fread()
succeeds. Additionally, this change fixes a GCC warning about ignoring
fread()’s return value.

[1]: <https://en.cppreference.com/w/cpp/io/c/fread>
This commit is contained in:
Jason Yundt
2024-05-10 08:31:56 -04:00
parent e042925001
commit d5e893fcb4
1 changed files with 1 additions and 2 deletions
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3
cfile/cfile.cpp
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@@ -147,8 +147,7 @@ int cf_OpenLibrary(const char *libname) {
mem_free(lib);
return 0; // CF_NO_FILE;
}
fread(id, HOG_TAG_LEN, 1, fp);
if (strncmp(id, HOG_TAG_STR, HOG_TAG_LEN)) {
if (!fread(id, HOG_TAG_LEN, 1, fp) || strncmp(id, HOG_TAG_STR, HOG_TAG_LEN)) {
fclose(fp);
mem_free(lib);
return 0; // CF_BAD_FILE;