[PATCH] rtld: Check __libc_enable_secure before honoring LD_PREFER_MAP_32BIT_EXEC...

The problem was introduced in glibc 2.23, in commit
b9eb92ab05204df772eb4929eccd018637c9f3e9
("Add Prefer_MAP_32BIT_EXEC to map executable pages with MAP_32BIT").

Gbp-Pq: Topic all
Gbp-Pq: Name git-CVE-2019-19126-rtld-Check-__libc_enable_secure-before-honoring-LD_P.diff

diff --git a/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h b/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
index 194369174df08946f620b4c30b28242ccf48fa6e..ac694c032e7baf872d5bebb757dc57beeeb80a7f 100644 (file)
--- a/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
+++ b/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
@@ -31,7 +31,8 @@
    environment variable, LD_PREFER_MAP_32BIT_EXEC.  */
 #define EXTRA_LD_ENVVARS \
   case 21:                                                               \
-    if (memcmp (envline, "PREFER_MAP_32BIT_EXEC", 21) == 0)              \
+    if (!__libc_enable_secure                                            \
+       && memcmp (envline, "PREFER_MAP_32BIT_EXEC", 21) == 0)            \
       GLRO(dl_x86_cpu_features).feature[index_arch_Prefer_MAP_32BIT_EXEC] \
        |= bit_arch_Prefer_MAP_32BIT_EXEC;                                \
     break;