[PATCH] libgcc: Fix eh_frame fast path in find_fde_tail

Florian Weimer fweimer@redhat.com
Tue Jun 6 09:51:26 GMT 2023


The eh_frame value is only used by linear_search_fdes, not the binary
search directly in find_fde_tail, so the bug is not immediately
apparent with most programs.

Fixes commit e724b0480bfa5ec04f39be8c7290330b495c59de ("libgcc:
Special-case BFD ld unwind table encodings in find_fde_tail").

[I'd appreciate suggestions how I could add a test for this.  BFD ld
does not seem to allow ommitting the binary search table.]

libgcc/

	PR libgcc/109712
	* unwind-dw2-fde-dip.c (find_fde_tail): Correct fast path for
	parsing eh_frame.

---
 libgcc/unwind-dw2-fde-dip.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libgcc/unwind-dw2-fde-dip.c b/libgcc/unwind-dw2-fde-dip.c
index 6223f5f18a2..4e0b880513f 100644
--- a/libgcc/unwind-dw2-fde-dip.c
+++ b/libgcc/unwind-dw2-fde-dip.c
@@ -403,8 +403,8 @@ find_fde_tail (_Unwind_Ptr pc,
 	 BFD ld generates.  */
       signed value __attribute__ ((mode (SI)));
       memcpy (&value, p, sizeof (value));
+      eh_frame = p + value;
       p += sizeof (value);
-      dbase = value;		/* No adjustment because pcrel has base 0.  */
     }
   else
     p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc,

base-commit: b327cbe8f4eefc91ee2bea49a1da7128adf30281



More information about the Gcc-patches mailing list