Hi, On Wed, Jun 13, 2018 at 1:38 PM, Junio C Hamano <gitster@xxxxxxxxx> wrote: > Eric Sunshine <sunshine@xxxxxxxxxxxxxx> writes: > >>> + buffer[size] = 0; /* assure that the buffer is still terminated */ >> >> I think we normally use '\0' for NUL on this project rather than simply 0. >> >> The comment is also effectively pure noise since it merely repeats >> what the code already states clearly (especially when the code says >> "buffer[size] = '\0';"), so dropping the comment altogether would be >> reasonable. > > Actually, I'd prefer to have comment there, but not about "what this > line does" (which is useless, as you pointed out) but about "why do > we do this seemingly redundant clearing". > > Here is what I tentatively came up with. > > -- >8 -- > From: Jeremy Linton <lintonrjeremy@xxxxxxxxx> > Date: Wed, 13 Jun 2018 09:22:07 -0500 > Subject: [PATCH] packfile: correct zlib buffer handling > > The buffer being passed to zlib includes a NUL terminator that git > needs to keep in place. unpack_compressed_entry() attempts to detect > the case that the source buffer hasn't been fully consumed by > checking to see if the destination buffer has been over consumed. > > This causes a problem, that more recent zlib patches have been > poisoning the unconsumed portions of the buffer which overwrites > the NUL byte, while correctly returning length and status. > > Let's place the NUL at the end of the buffer after inflate returns > to assure that it doesn't result in problems for git even if its > been overwritten by zlib. > > Signed-off-by: Jeremy Linton <lintonrjeremy@xxxxxxxxx> > Signed-off-by: Junio C Hamano <gitster@xxxxxxxxx> > --- > packfile.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/packfile.c b/packfile.c > index 4a5fe7ab18..d555699217 100644 > --- a/packfile.c > +++ b/packfile.c > @@ -1422,6 +1422,9 @@ static void *unpack_compressed_entry(struct packed_git *p, > return NULL; > } > > + /* versions of zlib can clobber unconsumed portion of outbuf */ > + buffer[size] = '\0'; > + > return buffer; > } > > -- > 2.18.0-rc1-1-g6f333ff2fb This is all fine with me, the original comment was an attempt to indicate that the original null may not have been there anymore too.. Shall I resubmit it as above, or can it be picked up like this?
