Sure. I was under the impression that |size| couldn't be both greater than 4 and a non-multiple of 4, but I've reworked the patch to incorporate this and to be a little more straightforward.
Is the only way to replace "ASAN" with "Address Sanitizer" to change the subject of this email thread? Anyway, here's a similar but modified patch: From: Myles C. Maxfield <my...@amazon.com> Date: Mon, 17 Jun 2013 11:50:05 -0700 Subject: [PATCH] Appeasing Address Sanitizer --- src/mesa/program/prog_parameter.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/src/mesa/program/prog_parameter.c b/src/mesa/program/prog_parameter.c index 95b153e..1d46476 100644 --- a/src/mesa/program/prog_parameter.c +++ b/src/mesa/program/prog_parameter.c @@ -155,7 +155,18 @@ _mesa_add_parameter(struct gl_program_parameter_list *paramList, p->Size = size; p->DataType = datatype; if (values) { - COPY_4V(paramList->ParameterValues[oldNum + i], values); + if (size >= (i+1)*4) { + COPY_4V(paramList->ParameterValues[oldNum + i], values); + } else { + /* silence asan */ + for (j = 0; j < 4; j++) { + if (i*4+j < size) { + paramList->ParameterValues[oldNum + i][j] = values[i*4+j]; + } else { + paramList->ParameterValues[oldNum + i][j].f = 0.0f; + } + } + } values += 4; p->Initialized = GL_TRUE; } -- 1.7.12.4 (Apple Git-37) On Mon, Jun 17, 2013 at 8:13 AM, Brian Paul <bri...@vmware.com> wrote: > On 06/14/2013 05:12 PM, Myles C. Maxfield wrote: > >> Sorry for the triple post; I received a bounce email the first time and >> got sent to the spam folder the second time, so I'm trying a third time. >> >> Hello, all. I was running Mesa with Address Sanitizer [1] turned on, and >> found one place where ASAN pointed out a read-before-initialized problem. >> In particular, in _mesa_add_parameter, in prog_parameter.c, |values| >> represents an array holding a variable number of values. These values get >> copied out of the array 4 at a time with the COPY_4V macro, however, the >> array might only contain a single element. In this case, ASAN reports a >> read-before-initialize because the last 3 of the 4 elements haven't been >> written to yet. I was hoping to contribute a patch that will silence this >> problem that ASAN reports. I'm happy to incorporate any feedback anyone has >> into this patch. >> >> Thanks, >> Myles C. Maxfield >> >> [1]https://code.google.com/p/**address-sanitizer/<https://code.google.com/p/address-sanitizer/> >> >> diff --git a/src/mesa/program/prog_**parameter.c b/src/mesa/program/prog_ >> **parameter.c >> index 2018fa5..63915fb 100644 >> --- a/src/mesa/program/prog_**parameter.c >> +++ b/src/mesa/program/prog_**parameter.c >> @@ -158,7 +158,17 @@ _mesa_add_parameter(struct gl_program_parameter_list >> *paramList, >> p->DataType = datatype; >> p->Flags = flags; >> if (values) { >> - COPY_4V(paramList->**ParameterValues[oldNum + i], values); >> + if (size & 3) { >> + for (j = 0; j < size; j++) { >> + paramList->ParameterValues[**oldNum + i][j] = values[j]; >> + } >> + /* silence asan */ >> + for (j = size; j < 4; j++) { >> + paramList->ParameterValues[**oldNum + i][j].f = 0; >> + } >> + } else { >> + COPY_4V(paramList->**ParameterValues[oldNum + i], values); >> + } >> values += 4; >> p->Initialized = GL_TRUE; >> } >> > > The value of 'size' can actually be greater than 4 (IIRC, and the function > comment are still correct). For example, for a matrix, size=16. So the > first for-loop should be fixed, just to be safe. > > In the commit message, let's not use "ASAN" since it's not obvious that it > means Address Sanitizer. > > -Brian > > > >
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