[v3,01/10] objtool: Do not assume order of parent/child functions
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Message ID 20200623172327.5701-2-kristen@linux.intel.com
State New
Headers show
Series
  • Function Granular KASLR
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Commit Message

Kristen Carlson Accardi June 23, 2020, 5:23 p.m. UTC
If a .cold function is examined prior to it's parent, the link
to the parent/child function can be overwritten when the parent
is examined. Only update pfunc and cfunc if they were previously
nil to prevent this from happening.

Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 tools/objtool/elf.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Comments

Josh Poimboeuf June 24, 2020, 3:08 a.m. UTC | #1
On Tue, Jun 23, 2020 at 10:23:18AM -0700, Kristen Carlson Accardi wrote:
> If a .cold function is examined prior to it's parent, the link
> to the parent/child function can be overwritten when the parent
> is examined. Only update pfunc and cfunc if they were previously
> nil to prevent this from happening.
> 
> Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>

FYI, this patch is now in the tip tree.

Patch
diff mbox series

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 84225679f96d..f953d3a15612 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -434,7 +434,13 @@  static int read_symbols(struct elf *elf)
 			size_t pnamelen;
 			if (sym->type != STT_FUNC)
 				continue;
-			sym->pfunc = sym->cfunc = sym;
+
+			if (sym->pfunc == NULL)
+				sym->pfunc = sym;
+
+			if (sym->cfunc == NULL)
+				sym->cfunc = sym;
+
 			coldstr = strstr(sym->name, ".cold");
 			if (!coldstr)
 				continue;