New resampler: ASan reports memcpy-param-overlap error

[SDLBugzilla]

This bug report was migrated from our old Bugzilla tracker.

Reported in version: HG 2.1
Reported for operating system, platform: Other, x86

Comments on the original bug report:

On 2017-09-26 04:46:03 +0000, Eric Wasylishen wrote:

Tested on https://hg.libsdl.org/SDL/rev/8ce1c541181d

To reproduce:

• download the test.wav that is attachmed to https://bugzilla.libsdl.org/show_bug.cgi?id=3846 (this is an 11000Hz sample)
• Run testresample with the arguments "test.wav out.wav 44100 2" in Xcode with Address Sanitizer enabled

It stops for me on the line:
SDL_memcpy(cvt->buf, dst, cvt->len_cvt); /* !!! FIXME: remove this if we can get the resampler to work in-place again. */

and I confirmed the memcpy is overwriting its input:

(lldb) print (char *)dst - (char *)cvt->buf
(long) $3 = 60672
(lldb) print cvt->len_cvt
(int) $4 = 243232

On 2017-10-03 22:37:45 +0000, Eric Wasylishen wrote:

Changing the SDL_memcpy to a SDL_memmove fixes the ASan warning and seems to work..

If I understand right, the memcpy is copying "output" (which is directly after "input" in a single buffer), over top of "input", which is OK, it just needs to be a memmove instead of memcpy:

[ input ] [ output (possibly longer than input) ]

-->

[ output (possibly longer than input) ] [ unused ]

On 2017-10-11 02:32:18 +0000, Ryan C. Gordon wrote:

Yeah, you're right, this should be a memmove.

Fixed in https://hg.libsdl.org/SDL/rev/f882930f174f, thanks!

--ryan.