git: 7953cbaabe7c - main - libc: Reassociate pointer arithmetic in __libc_tls_get_addr

From: Jessica Clarke <jrtc27_at_FreeBSD.org>
Date: Wed, 07 May 2025 19:22:05 UTC
The branch main has been updated by jrtc27:

URL: https://cgit.FreeBSD.org/src/commit/?id=7953cbaabe7c35d439f0222481a12ad52d0b0df0

commit 7953cbaabe7c35d439f0222481a12ad52d0b0df0
Author:     Jessica Clarke <jrtc27@FreeBSD.org>
AuthorDate: 2025-05-07 19:19:42 +0000
Commit:     Jessica Clarke <jrtc27@FreeBSD.org>
CommitDate: 2025-05-07 19:19:42 +0000

    libc: Reassociate pointer arithmetic in __libc_tls_get_addr
    
    Rather than compute a biased pointer only to then un-bias it again, un-bias
    the offset before adding it to the DTV entry.
    
    This mirrors rtld-elf commit d71c97026366 ("rtld-elf: Push
    TLS_DTV_OFFSET into tls_get_addr_common's arguments")
    
    Reviewed by:    kib
    Differential Revision:  https://reviews.freebsd.org/D50224
---
 lib/libc/gen/tls.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/libc/gen/tls.c b/lib/libc/gen/tls.c
index 8d453eccb801..218cd1da92df 100644
--- a/lib/libc/gen/tls.c
+++ b/lib/libc/gen/tls.c
@@ -85,8 +85,8 @@ __libc_tls_get_addr(void *vti)
 
 	dtv = _tcb_get()->tcb_dtv;
 	ti = vti;
-	return ((char *)(dtv[ti->ti_module + 1] + ti->ti_offset) +
-	    TLS_DTV_OFFSET);
+	return ((char *)dtv[ti->ti_module + 1] + (ti->ti_offset +
+	    TLS_DTV_OFFSET));
 }
 
 #ifdef __i386__