From: Florian Weimer <fweimer@redhat.com>
To: libc-stable@sourceware.org
Subject: [2.29 COMMITTED] rtld: Check __libc_enable_secure before honoring LD_PREFER_MAP_32BIT_EXEC (CVE-2019-19126) [BZ #25204]
Date: Tue, 01 Jan 2019 00:00:00 -0000 [thread overview]
Message-ID: <20191122123507.DFCB7B703A14@oldenburg2.str.redhat.com> (raw)
From: Marcin Kościelnicki <mwk@0x04.net>
The problem was introduced in glibc 2.23, in commit
b9eb92ab05204df772eb4929eccd018637c9f3e9
("Add Prefer_MAP_32BIT_EXEC to map executable pages with MAP_32BIT").
(cherry picked from commit d5dfad4326fc683c813df1e37bbf5cf920591c8e)
Change-Id: Ib782573b4623ee3edfa9f98ad62f69b9d8edcb27
diff --git a/NEWS b/NEWS
index 5dc41ff3eb..4ad7c47d5f 100644
--- a/NEWS
+++ b/NEWS
@@ -35,6 +35,7 @@ The following bugs are resolved with this release:
[24744] io: Remove the copy_file_range emulation
[24986] alpha: new getegid, geteuid and getppid syscalls used
unconditionally
+ [25204] Ignore LD_PREFER_MAP_32BIT_EXEC for SUID programs
Security related changes:
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 975cbe2950..df2cdfdb6b 100644
--- 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;
reply other threads:[~2019-11-22 12:35 UTC|newest]
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