Don't leak memory on realloc failure

[ngie]

Summary

Don't leak memory on realloc failure

Use reallocf instead of realloc to free on failure and deal with the
failure case more gracefully by freeing memory.

If anything fails, free buf as well as bufp.

Reported by: cppcheck
Sponsored by: EMC / Isilon Storage Division

[araujo]

LGTM!

[markj]

lib/libkvm/kvm_proc.c

671

This doesn't seem right. buf is static, so we'll leak memory here if the previous call succeeded.

[ngie]

lib/libkvm/kvm_proc.c

671

Yeah, you're right. I missed that it was static... that reduces the diff a lot

[ngie]

I need to step back and look at this a bit more. This function is confusing.. I'll handle the other CRs first.

[jhb]

lib/libkvm/kvm_proc.c

671

The idea is that the library keeps a single buffer allocated (since the caller uses the return value) and that the returned buffer remains valid until the next call to kvm_getprocs(). This is noted in the manpage.

Contrast this with kinfo_getprocs() in libutil which hands the returned buffer off to the caller which is required to free(3) it. (This seems more sane to me, but kvm_getargv()'s API is rather set at this point.)

In that sense I think you should not use reallocf() or free on failure, but keep the buffer around. However, you should fix the leak by using a temporary variable for the return value of realloc() and only updating 'bufp' and 'argc' if realloc succeeds. The code is careful to do this earlier when resizing 'buf' in the 'nchr > buflen' case at line 690.

This does mean that you can also avoid the goto's and just fix the returns to use NULL instead of 0.

[ngie]

• Remove goto/free complexity that broke general re-use.
• Ensure the bufp malloc succeeds before continuing; if it fails, free buf to get back to a relatively clean slate.
• Convert the reallocf back to a realloc, and instead use a temporary buffer for capturing the result of the realloc and reassigning bufp if successful.

[ngie]

Ping?

[markj]

lib/libkvm/kvm_proc.c

685

We need to set argc before doing this.

[ngie]

lib/libkvm/kvm_proc.c

685

Derp... yes.

[ngie]

Move argc assignment back up.