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| author | Marcin Kościelnicki <mwk@0x04.net> | 2019-11-21 00:20:15 +0100 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2019-11-22 13:46:54 +0100 |
| commit | 7966ce07e89fa4ccc8fdba00d4439fc652862462 (patch) | |
| tree | a40a5fcae478b1a336ea11b70ee5ded1307a0808 | |
| parent | cedb3e47c68d319607736a820da2d5b3b8ddff6f (diff) | |
| download | glibc-7966ce07e89fa4ccc8fdba00d4439fc652862462.tar.gz glibc-7966ce07e89fa4ccc8fdba00d4439fc652862462.tar.xz glibc-7966ce07e89fa4ccc8fdba00d4439fc652862462.zip | |
rtld: Check __libc_enable_secure before honoring LD_PREFER_MAP_32BIT_EXEC (CVE-2019-19126) [BZ #25204]
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)
| -rw-r--r-- | NEWS | 8 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h | 3 |
2 files changed, 10 insertions, 1 deletions
diff --git a/NEWS b/NEWS index f249ff690c..2a97ce5dac 100644 --- a/NEWS +++ b/NEWS @@ -69,6 +69,7 @@ The following bugs are resolved with this release: [24228] old x86 applications that use legacy libio crash on exit [24476] dlfcn: Guard __dlerror_main_freeres with __libc_once_get (once) [24744] io: Remove the copy_file_range emulation. + [25204] Ignore LD_PREFER_MAP_32BIT_EXEC for SUID programs Security related changes: @@ -97,6 +98,13 @@ Security related changes: CVE-2019-9169: Attempted case-insensitive regular-expression match via proceed_next_node in posix/regexec.c leads to heap-based buffer over-read. Reported by Hongxu Chen. + + CVE-2019-19126: ld.so failed to ignore the LD_PREFER_MAP_32BIT_EXEC + environment variable during program execution after a security + transition, allowing local attackers to restrict the possible mapping + addresses for loaded libraries and thus bypass ASLR for a setuid + program. Reported by Marcin Kościelnicki. + Version 2.28 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 194369174d..ac694c032e 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; |