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Remove default /var/tmp for LD_PROFILE_OUTPUT (RHEL-142194)

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Resolves: RHEL-142194
This commit is contained in:
Florian Weimer 2026-01-19 09:06:11 +01:00
parent c06d37dd95
commit 383c532ed6
2 changed files with 89 additions and 1 deletions
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84
glibc-RHEL-142194.patch Normal file
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@ -0,0 +1,84 @@
commit 7b543dcdf97d07fd4346feb17916e08fe83ad0ae
Author: Florian Weimer <fweimer@redhat.com>
Date: Thu Jan 15 22:29:46 2026 +0100
elf: Ignore LD_PROFILE if LD_PROFILE_OUTPUT is not set (bug 33797)
The previous default for LD_PROFILE_OUTPUT, /var/tmp, is insecure
because it's typically a 1777 directory, and other systems could
place malicious files there which interfere with execution.
Requiring the user to specify a profiling directory mitigates
the impact of bug 33797. Clear LD_PROFILE_OUTPUT alongside
with LD_PROFILE.
Rework the test not to use predictable file names.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Conflicts:
elf/rtld.c
(different implementation of environment variable filtering
downstream, incorporate changes from upstream commit
4a133885a7c8ae7ebe34e36fcdb353f8e94c810f, adjust for
GLRO(_dl_profile_output) use in glibc-rh2047981-44.patch)
elf/tst-env-setuid.c
(no LD_PROFILE test downstream)
diff --git a/elf/rtld.c b/elf/rtld.c
index 48698f93a4873a6d..848f6f51d093f313 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -2684,11 +2684,9 @@ process_envvars (struct dl_main_state *state)
char *envline;
char *debug_output = NULL;
- /* This is the default place for profiling data file. As a side
- effect, this marks ld.so as initialized, so that the rtld_active
- function returns true from now on. */
- GLRO(dl_profile_output)
- = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
+ /* This marks ld.so as initialized, so that the rtld_active function
+ returns true from now on. "" means no default. */
+ GLRO(dl_profile_output) = "";
while ((envline = _dl_next_ld_env_entry (&runp)) != NULL)
{
@@ -2738,7 +2736,8 @@ process_envvars (struct dl_main_state *state)
}
/* Which shared object shall be profiled. */
- if (memcmp (envline, "PROFILE", 7) == 0 && envline[8] != '\0')
+ if (!__libc_enable_secure
+ && memcmp (envline, "PROFILE", 7) == 0 && envline[8] != '\0')
GLRO(dl_profile) = &envline[8];
break;
@@ -2899,6 +2898,15 @@ process_envvars (struct dl_main_state *state)
/* We use standard output if opening the file failed. */
GLRO(dl_debug_fd) = STDOUT_FILENO;
}
+
+ /* There is no fixed, safe directory to store profiling data, so
+ activate LD_PROFILE only if LD_PROFILE_OUTPUT is set as well. */
+ if (GLRO(dl_profile) != NULL && *GLRO(dl_profile_output) == '\0')
+ {
+ _dl_error_printf ("\
+warning: LD_PROFILE ignored because LD_PROFILE_OUTPUT not specified\n");
+ GLRO(dl_profile) = NULL;
+ }
}
#if HP_TIMING_INLINE
diff --git a/sysdeps/generic/unsecvars.h b/sysdeps/generic/unsecvars.h
index 5ea8a4a259ef753c..0b84642f71ae9351 100644
--- a/sysdeps/generic/unsecvars.h
+++ b/sysdeps/generic/unsecvars.h
@@ -21,6 +21,7 @@
"LD_ORIGIN_PATH\0" \
"LD_PRELOAD\0" \
"LD_PROFILE\0" \
+ "LD_PROFILE_OUTPUT\0" \
"LD_SHOW_AUXV\0" \
"LD_USE_LOAD_BIAS\0" \
"LOCALDOMAIN\0" \

6
glibc.spec
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@ -115,7 +115,7 @@ end \
Summary: The GNU libc libraries
Name: glibc
Version: %{glibcversion}
Release: %{glibcrelease}.29
Release: %{glibcrelease}.30
# In general, GPLv2+ is used by programs, LGPLv2+ is used for
# libraries.
@ -1296,6 +1296,7 @@ Patch1061: glibc-RHEL-72011-6.patch
Patch1062: glibc-RHEL-72011-7.patch
Patch1063: glibc-RHEL-72011-8.patch
Patch1064: glibc-RHEL-141849.patch
Patch1065: glibc-RHEL-142194.patch
##############################################################################
# Continued list of core "glibc" package information:
@ -2957,6 +2958,9 @@ fi
%{_libdir}/libpthread_nonshared.a
%changelog
* Mon Jan 19 2026 Florian Weimer <fweimer@redhat.com> - 2.28-251.30
- Remove default /var/tmp for LD_PROFILE_OUTPUT (RHEL-142194)
* Mon Jan 19 2026 Florian Weimer <fweimer@redhat.com> - 2.28-251.29
- rpminspect.yaml: note that glibc-minimal-langpack is empty (RHEL-123889)