inflate_fast() implements possibility to be build with
POSTINC set or unset. That POSTINC macro was introduced by
commit e89516f031db ("zlib: split up to match original source tree")
but forced to #undef in zlib.h.
However, in the meantime that commit removed UP_UNALIGNED() macro
introduced by commit cd514aeb996e ("zlib: Optimize decompression")
that was meant to implement proper behaviour depending on POSTINC.
In addition, commit cd514aeb996e ("zlib: Optimize decompression") has
a bug for when POSTINC is set in the following pointer arithmetic:
pat16 = *(sout-2+2*OFF)
The intension is to remove 2 bytes when OFF is 0, but sout being a
short, this leads to removing 4 bytes instead of 2. The bug in not
visible when OFF is set to 1 which has always been the case until now.
In preparation for followup patch that will activate POSTINC, add back
UP_UNALIGNED() macro and fix the above pointer calculation.
Fixes: cd514aeb996e ("zlib: Optimize decompression")
Cc: Michal Simek <michal.si...@amd.com>
Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
---
lib/zlib/inffast.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/lib/zlib/inffast.c b/lib/zlib/inffast.c
index bdaa6d0dc5..29ec72fce5 100644
--- a/lib/zlib/inffast.c
+++ b/lib/zlib/inffast.c
@@ -26,9 +26,11 @@
#ifdef POSTINC
# define OFF 0
# define PUP(a) *(a)++
+# define UP_UNALIGNED(a) get_unaligned((a)++)
#else
# define OFF 1
# define PUP(a) *++(a)
+# define UP_UNALIGNED(a) get_unaligned(++(a))
#endif
/*
@@ -270,14 +272,14 @@ void inflate_fast(z_streamp strm, unsigned start)
sfrom = (unsigned short *)(from - OFF);
loops = len >> 1;
do
- PUP(sout) = get_unaligned(++sfrom);
+ PUP(sout) = UP_UNALIGNED(sfrom);
while (--loops);
out = (unsigned char *)sout + OFF;
from = (unsigned char *)sfrom + OFF;
} else { /* dist == 1 or dist == 2 */
unsigned short pat16;
- pat16 = *(sout-2+2*OFF);
+ pat16 = *(sout - 1 + OFF);
if (dist == 1)
#if defined(__BIG_ENDIAN)
pat16 = (pat16 & 0xff) | ((pat16 & 0xff ) << 8);
--
2.44.0
