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x86: Undo return-thunk damage

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commit 15e67227c49a57837108acfe1c80570e1bd9f962 upstream.

Introduce X86_FEATURE_RETHUNK for those afflicted with needing this.

  [ bp: Do only INT3 padding - simpler. ]

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
[cascardo: CONFIG_STACK_VALIDATION vs CONFIG_OBJTOOL]
[cascardo: no IBT support]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Zijlstra
2022-06-14 23:15:37 +02:00
committed by Greg Kroah-Hartman
parent 270de63cf4
commit 716410960b
6 changed files with 78 additions and 2 deletions
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8
arch/x86/kernel/module.c
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@@ -252,7 +252,7 @@ int module_finalize(const Elf_Ehdr *hdr,
{
const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
*para = NULL, *orc = NULL, *orc_ip = NULL,
*retpolines = NULL;
*retpolines = NULL, *returns = NULL;
char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
@@ -270,12 +270,18 @@ int module_finalize(const Elf_Ehdr *hdr,
orc_ip = s;
if (!strcmp(".retpoline_sites", secstrings + s->sh_name))
retpolines = s;
if (!strcmp(".return_sites", secstrings + s->sh_name))
returns = s;
}
if (retpolines) {
void *rseg = (void *)retpolines->sh_addr;
apply_retpolines(rseg, rseg + retpolines->sh_size);
}
if (returns) {
void *rseg = (void *)returns->sh_addr;
apply_returns(rseg, rseg + returns->sh_size);
}
if (alt) {
/* patch .altinstructions */
void *aseg = (void *)alt->sh_addr;