You have been subscribed to a public bug: Hello. I found a terrible bug in memory copy routine (eglibc-2.11.1/sysdeps/i386/i686/multiarch/memcpy-ssse3-rep.S and memcpy-ssse3.S). Here is the code
movl LEN(%esp), %ecx movl SRC(%esp), %eax movl DEST(%esp), %edx ...... L(fwd_write_less32bytes): #ifndef USE_AS_MEMMOVE cmp %dl, %al -----<<<<< BUG !!! jb L(bk_write) Assume, that I have an array of char AR and I want move data from AR[10] to AR[0] with length 47. Data should be copied in forward direction. Problem is when AR[10] overlaps 255 bytes boundary. For example address of AR[0] is 0x000000F8 (EDX) and address of AR[10] is 0x00000102 (EAX) then cmp %dl,%al return AL as smaller then DL and the data are copied in reverse direction that causes data corruption. In reality it will cause problems on Ubuntu 10.04 mod_ssl in Apache with last updates installed (libc6: Installed: 2.11.1-0ubuntu7.2), which are sometimes unable to process the HTTP header because of malformed data, but may cause other unexpected behavior (bug #595116, bug #595855, bug #589611 and maybe others). I don't know if only this two files is affected by this bug. See GDB snapshot in attachment Regards Jiri Engelthaler ** Affects: apache2 (Ubuntu) Importance: Undecided Status: New -- Critical bug in memcpy-ssse3-rep.S https://bugs.launchpad.net/bugs/609290 You received this bug notification because you are a member of Ubuntu Server Team, which is subscribed to apache2 in ubuntu. -- Ubuntu-server-bugs mailing list Ubuntu-server-bugs@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs