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| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2026-04-28 07:15:52 +0300 |
|---|---|---|
| committer | Josh Poimboeuf <jpoimboe@kernel.org> | 2026-05-05 07:16:07 +0300 |
| commit | f7ceffd21a8a59ba1e92078750eef86e628dea80 (patch) | |
| tree | 4973f2eb95ebb166ee2d9769e00592c21724afcc | |
| parent | fc0bb9915bce0c333f918ca76958d804ccd79f89 (diff) | |
| download | linux-f7ceffd21a8a59ba1e92078750eef86e628dea80.tar.xz | |
objtool/klp: Fix kCFI prefix finding/cloning
With CFI+CALL_PADDING, Clang places .Ltmp labels at the start of the NOP
padding (offset 5) between the __cfi_ prefix and the function entry
point. get_func_prefix() only checks the immediately previous symbol,
so the intervening .Ltmp label causes it to miss the __cfi_ prefix
symbol.
This results in klp-diff not cloning the kCFI type hash into the
livepatch module, causing a CFI failure at module load when calling
callback functions through indirect calls:
CFI failure at __klp_enable_patch+0xab/0x140
(target: pre_patch_callback+0x0/0x80 [livepatch_combined];
expected type: 0xde073954)
Instead of walking backward through the section's symbol list, just use
find_func_containing() for the byte before the function. This works now
that __cfi_ symbols are being grown by objtool to fill the padding.
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
| -rw-r--r-- | tools/objtool/include/objtool/elf.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h index 305183f30a33..fccf72cbd343 100644 --- a/tools/objtool/include/objtool/elf.h +++ b/tools/objtool/include/objtool/elf.h @@ -539,10 +539,10 @@ static inline struct symbol *get_func_prefix(struct symbol *func) { struct symbol *prev; - if (!is_func_sym(func)) + if (!is_func_sym(func) || !func->offset) return NULL; - prev = sec_prev_sym(func); + prev = find_func_containing(func->sec, func->offset - 1); if (prev && is_prefix_func(prev)) return prev; |