25 lines
1.1 KiB
Diff
25 lines
1.1 KiB
Diff
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commit d5dfad4326fc683c813df1e37bbf5cf920591c8e
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Author: Marcin Kościelnicki <mwk@0x04.net>
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Date: Thu Nov 21 00:20:15 2019 +0100
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rtld: Check __libc_enable_secure before honoring LD_PREFER_MAP_32BIT_EXEC (CVE-2019-19126) [BZ #25204]
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The problem was introduced in glibc 2.23, in commit
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b9eb92ab05204df772eb4929eccd018637c9f3e9
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("Add Prefer_MAP_32BIT_EXEC to map executable pages with MAP_32BIT").
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diff --git a/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h b/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
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index 194369174df08946..ac694c032e7baf87 100644
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--- a/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
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+++ b/sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
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@@ -31,7 +31,8 @@
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environment variable, LD_PREFER_MAP_32BIT_EXEC. */
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#define EXTRA_LD_ENVVARS \
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case 21: \
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- if (memcmp (envline, "PREFER_MAP_32BIT_EXEC", 21) == 0) \
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+ if (!__libc_enable_secure \
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+ && memcmp (envline, "PREFER_MAP_32BIT_EXEC", 21) == 0) \
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GLRO(dl_x86_cpu_features).feature[index_arch_Prefer_MAP_32BIT_EXEC] \
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|= bit_arch_Prefer_MAP_32BIT_EXEC; \
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break;
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