Patchwork [11/17,v6] De-PLTize __stack_chk_fail internal calls within libc.so.

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Submitter Nix
Date March 13, 2016, 3:16 p.m.
Message ID <1457882222-22599-12-git-send-email-nix@esperi.org.uk>
Download mbox | patch
Permalink /patch/11319/
State New
Headers show

Comments

Nix - March 13, 2016, 3:16 p.m.
From: Adhemerval Zanella <adhemerval.zanella@linaro.org>

We use the same assembler-macro trick we use to de-PLTize
compiler-generated libcalls to memcpy and memset to redirect
__stack_chk_fail to __stack_chk_fail_local.

v5: New.
v6: Only do it within the shared library: with __stack_chk_fail_local
    in libc_pic.a now we don't need to worry about calls from inside
    other routines in libc_nonshared.a any more.

	* sysdeps/generic/symbol-hacks.h (__stack_chk_fail): Add internal
	alias.
---
 sysdeps/generic/symbol-hacks.h | 6 ++++++
 1 file changed, 6 insertions(+)

Patch

diff --git a/sysdeps/generic/symbol-hacks.h b/sysdeps/generic/symbol-hacks.h
index ce576c9..fd3d2de 100644
--- a/sysdeps/generic/symbol-hacks.h
+++ b/sysdeps/generic/symbol-hacks.h
@@ -5,3 +5,9 @@  asm ("memmove = __GI_memmove");
 asm ("memset = __GI_memset");
 asm ("memcpy = __GI_memcpy");
 #endif
+
+/* -fstack-protector generates calls to __stack_chk_fail, which need
+   similar adjustments to avoid going through the PLT.  */
+#if !defined __ASSEMBLER__ && IS_IN (libc) && defined SHARED
+asm ("__stack_chk_fail = __stack_chk_fail_local");
+#endif