https://git.busybox.net/busybox/commit/?id=ca96022d6edaaf619324db5a481698231d74d1df From ca96022d6edaaf619324db5a481698231d74d1df Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?S=C3=B6ren=20Tempel?= Date: Tue, 8 Feb 2022 20:29:30 +0100 Subject: ed: don't use memcpy with overlapping memory regions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The memcpy invocations in the subCommand function, modified by this commit, previously used memcpy with overlapping memory regions. This is undefined behavior. On Alpine Linux, it causes BusyBox ed to crash since we compile BusyBox with -D_FORTIFY_SOURCE=2 and our fortify-headers implementation catches this source of undefined behavior [0]. The issue can only be triggered if the replacement string is the same size or shorter than the old string. Looking at the code, it seems to me that a memmove(3) is what was actually intended here, this commit modifies the code accordingly. [0]: https://gitlab.alpinelinux.org/alpine/aports/-/issues/13504 Signed-off-by: Sören Tempel Signed-off-by: Denys Vlasenko --- a/editors/ed.c +++ b/editors/ed.c @@ -720,7 +720,7 @@ static void subCommand(const char *cmd, int num1, int num2) if (deltaLen <= 0) { memcpy(&lp->data[offset], newStr, newLen); if (deltaLen) { - memcpy(&lp->data[offset + newLen], + memmove(&lp->data[offset + newLen], &lp->data[offset + oldLen], lp->len - offset - oldLen); -- cgit v1.2.3