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authorBorislav Petkov (AMD) <bp@alien8.de>2023-06-28 12:02:39 +0300
committerBorislav Petkov (AMD) <bp@alien8.de>2023-07-27 12:07:14 +0300
commitfb3bd914b3ec28f5fb697ac55c4846ac2d542855 (patch)
tree7f5bfb82aa0ee0ce648eaf7ac79af55bdced1d9d /tools/objtool
parent0e52740ffd10c6c316837c6c128f460f1aaba1ea (diff)
downloadlinux-fb3bd914b3ec28f5fb697ac55c4846ac2d542855.tar.xz
x86/srso: Add a Speculative RAS Overflow mitigation
Add a mitigation for the speculative return address stack overflow vulnerability found on AMD processors. The mitigation works by ensuring all RET instructions speculate to a controlled location, similar to how speculation is controlled in the retpoline sequence. To accomplish this, the __x86_return_thunk forces the CPU to mispredict every function return using a 'safe return' sequence. To ensure the safety of this mitigation, the kernel must ensure that the safe return sequence is itself free from attacker interference. In Zen3 and Zen4, this is accomplished by creating a BTB alias between the untraining function srso_untrain_ret_alias() and the safe return function srso_safe_ret_alias() which results in evicting a potentially poisoned BTB entry and using that safe one for all function returns. In older Zen1 and Zen2, this is accomplished using a reinterpretation technique similar to Retbleed one: srso_untrain_ret() and srso_safe_ret(). Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Diffstat (limited to 'tools/objtool')
-rw-r--r--tools/objtool/arch/x86/decode.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 2e1caabecb18..2d51fa8da9e8 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -824,5 +824,8 @@ bool arch_is_retpoline(struct symbol *sym)
bool arch_is_rethunk(struct symbol *sym)
{
- return !strcmp(sym->name, "__x86_return_thunk");
+ return !strcmp(sym->name, "__x86_return_thunk") ||
+ !strcmp(sym->name, "srso_untrain_ret") ||
+ !strcmp(sym->name, "srso_safe_ret") ||
+ !strcmp(sym->name, "__ret");
}