On AIX 7.2 in 32-bit mode, I see a test failure: ../../build-aux/test-driver[111]: 14156200 Segmentation fault(coredump) FAIL: test-memchr
Investigation shows that the code accesses the second word of the indicated memory region, even if the searched byte already occurs in the first word of the memory region: (gdb) disassemble memchr Dump of assembler code for function memchr: ... 0xd0141888 <+104>: lwz r8,0(r3) => 0xd014188c <+108>: lwz r9,4(r3) (gdb) print (void *)$r3 $2 = (void *) 0x30002ffc For glibc this was classified as a glibc bug <https://sourceware.org/bugzilla/show_bug.cgi?id=10162>, and worked around in Gnulib. The same criteria apply here. 2020-12-11 Bruno Haible <br...@clisp.org> memchr: Work around memory overrun bug on AIX 7.2. * m4/memchr.m4 (gl_FUNC_MEMCHR): Test against AIX 7.2 bug. * doc/posix-functions/memchr.texi: Mention the AIX bug. diff --git a/doc/posix-functions/memchr.texi b/doc/posix-functions/memchr.texi index 5ceb71f..98ef20e 100644 --- a/doc/posix-functions/memchr.texi +++ b/doc/posix-functions/memchr.texi @@ -10,7 +10,7 @@ Portability problems fixed by Gnulib: @itemize @item This function dereferences too much memory on some platforms: -glibc 2.10 on x86_64, IA-64; glibc 2.11 on Alpha. +glibc 2.10 on x86_64, IA-64; glibc 2.11 on Alpha, AIX 7.2. @item This function returns NULL if the character argument is not in the range of an @code{unsigned char} on some platforms: diff --git a/m4/memchr.m4 b/m4/memchr.m4 index 81e8f98..888d2b2 100644 --- a/m4/memchr.m4 +++ b/m4/memchr.m4 @@ -1,4 +1,4 @@ -# memchr.m4 serial 16 +# memchr.m4 serial 17 dnl Copyright (C) 2002-2004, 2009-2020 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -59,6 +59,7 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR], #endif if (fence) { + /* Test against bugs on glibc systems. */ if (memchr (fence, 0, 0)) result |= 1; strcpy (fence - 9, "12345678"); @@ -66,6 +67,9 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR], result |= 2; if (memchr (fence - 1, 0, 3) != fence - 1) result |= 4; + /* Test against bug on AIX 7.2. */ + if (memchr (fence - 4, '6', 16) != fence - 4) + result |= 8; } /* Test against bug on Android 4.3. */ { @@ -74,7 +78,7 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR], input[1] = 'b'; input[2] = 'c'; if (memchr (input, 0x789abc00 | 'b', 3) != input + 1) - result |= 8; + result |= 16; } return result; ]])],
