From: Nathan Moinvaziri <nathan@nathanm.com>
Date: Sun, 11 Jan 2026 00:13:54 +0000 (-0800)
Subject: Fixed UB in adler32_avx512_copy storemask when len is 0.
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a17bae48614ea02f6a2abdacd3f293a5f0740338;p=thirdparty%2Fzlib-ng.git

Fixed UB in adler32_avx512_copy storemask when len is 0.
---

diff --git a/arch/x86/adler32_avx512.c b/arch/x86/adler32_avx512.c
index 8ebaf50b2..545806bfc 100644
--- a/arch/x86/adler32_avx512.c
+++ b/arch/x86/adler32_avx512.c
@@ -26,7 +26,7 @@ Z_FORCEINLINE static uint32_t adler32_copy_impl(uint32_t adler, uint8_t *dst, co
 rem_peel:
     if (len < 64) {
         /* This handles the remaining copies, just call normal adler checksum after this */
-        if (COPY) {
+        if (COPY && len) {
             __mmask64 storemask = (0xFFFFFFFFFFFFFFFFUL >> (64 - len));
             __m512i copy_vec = _mm512_maskz_loadu_epi8(storemask, src);
             _mm512_mask_storeu_epi8(dst, storemask, copy_vec);