From: Nathan Mills <the.true.nathan.mills@gmail.com>
To: linux-btrfs@vger.kernel.org
Subject: Inspect command leaks memory if realloc() fails
Date: Fri, 5 Apr 2024 08:55:00 -0700 [thread overview]
Message-ID: <CALjJ9cdoxY7E4omFtXcZigNV9Q8_+q95do=b=PrzsN+JbBK23Q@mail.gmail.com> (raw)
In `cmd_inspect_list_chunks()` in Btrfs v6.8-g3793e987 on the master
branch, there is this code on line 1167:
```c
ctx.stats = realloc(ctx.stats, ctx.size * sizeof(ctx.stats[0]));
```
This is a "common realloc mistake" according to CppCheck. The fix is
to assign the result of realloc to a temporary variable and only
assign the original variable if the temp is non-NULL. That way we
don't lose the pointer to the old memory.
I found this by grepping the source for this regex:
`([A-Za-z_0-9->\.]+)\s*=\s*realloc\s*\(\s*\1` after noticing a
CppCheck warning for a different part of btrfs that already uses a
temporary to hold the reallocated memory.
Here's a patch to fix it (note: this patch probably won't apply to
devel because the goto label has been changed in `v6.8-19-g512fa7e6`):
commit 7f65051ee07a46a9cb7e0aa0134af0cc77db0a16 (HEAD ->
realloc-memory-leak, myfork/realloc-memory-leak)
Author: Nathan Mills <38995150+Quipyowert2@users.noreply.github.com>
Date: Thu Apr 4 19:34:28 2024 -0700
btrfs-progs: cmds: fix inspect memory leak.
diff --git a/cmds/inspect.c b/cmds/inspect.c
index 145196d0..e665a281 100644
--- a/cmds/inspect.c
+++ b/cmds/inspect.c
@@ -1162,12 +1162,15 @@ static int cmd_inspect_list_chunks(const
struct cmd_struct *cmd,
if (ctx.length == ctx.size) {
ctx.size += 1024;
- ctx.stats = realloc(ctx.stats, ctx.size
+ struct list_chunks_entry *tmp;
+ tmp = realloc(ctx.stats, ctx.size
* sizeof(ctx.stats[0]));
- if (!ctx.stats) {
+ if (!tmp) {
ret = 1;
error_msg(ERROR_MSG_MEMORY, NULL);
goto out_nomem;
+ } else {
+ ctx.stats = tmp;
}
}
}
reply other threads:[~2024-04-05 15:55 UTC|newest]
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