From: Jim Meyering <jim@meyering.net>
Date: Mon, 26 Feb 2007 23:11:35 +0000 (+0100)
Subject: diff --cc: integer overflow given a 2GB-or-larger file
X-Git-Tag: v1.5.0.3~39
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/ee24ee55c28e46b502e4e2d219feced5a5d67e6b?hp=ee24ee55c28e46b502e4e2d219feced5a5d67e6b

diff --cc: integer overflow given a 2GB-or-larger file

Few of us use git to compare or even version-control 2GB files,
but when we do, we'll want it to work.

Reading a recent patch, I noticed two lines like this:

int len = st.st_size;

Instead of "int", that should be "size_t".  Otherwise, in the
non-symlink case, with 64-bit size_t, if the file's size is 2GB,
the following xmalloc will fail:

result = xmalloc(len + 1);

trying to allocate 2^64 - 2^31 + 1 bytes (assuming sign-extension
in the int-to-size_t promotion).  And even if it didn't fail, the
subsequent "result[len] = 0;" would be equivalent to an unpleasant
"result[-2147483648] = 0;"

The other nearby "int"-declared size variable, sz, should also be of
type size_t, for the same reason.  If sz ever wraps around and becomes
negative, xread will corrupt memory _before_ the "result" buffer.

Signed-off-by: Jim Meyering <jim@meyering.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>
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