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Bug 3849

Summary: New resampler: ASan reports memcpy-param-overlap error
Product: SDL Reporter: Eric Wasylishen <ewasylishen>
Component: audioAssignee: Ryan C. Gordon <icculus>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2 CC: sezeroz
Version: HG 2.1   
Hardware: x86   
OS: Other   

Description Eric Wasylishen 2017-09-26 04:46:03 UTC 
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
Comment 1 Eric Wasylishen 2017-10-03 22:37:45 UTC 
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 ]
Comment 2 Ryan C. Gordon 2017-10-11 02:32:18 UTC 
Yeah, you're right, this should be a memmove.

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

--ryan.