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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 13:40:07 +0100 |
| commit | 4d5cfeb510125345cb41431afc9022492994cffa (patch) | |
| tree | 52d2d51829353010062b266ae4b3e0a1055ceb17 | |
| parent | 92f04eedb50dc12643addbcb033a06b51633d0ff (diff) | |
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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 | 7 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h | 3 |
2 files changed, 9 insertions, 1 deletions
@@ -67,6 +67,12 @@ Security related changes: memcmp gave the wrong result since it treated the size argument as zero. Reported by H.J. Lu. + 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. + The following bugs are resolved with this release: [6889] 'PWD' mentioned but not specified @@ -145,6 +151,7 @@ The following bugs are resolved with this release: [24228] old x86 applications that use legacy libio crash on exit [24531] Malloc tunables give tcache assertion failures [24744] io: Remove the copy_file_range emulation + [25204] Ignore LD_PREFER_MAP_32BIT_EXEC for SUID programs Version 2.27 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; |