git: a4ee0edc4a0b - main - libc: Make elf_aux_info() return an error if AT_USRSTACK* is undefined

The branch main has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=a4ee0edc4a0b3f880463021c7ae1bdcf7112f3d6

commit a4ee0edc4a0b3f880463021c7ae1bdcf7112f3d6
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2022-10-18 22:11:26 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2022-10-18 22:11:26 +0000

    libc: Make elf_aux_info() return an error if AT_USRSTACK* is undefined
    
    Otherwise we do not fall back to sysctls if the auxv entries are not
    defined by the kernel.  Arguably this is not a bug since we do not
    support newer libc running on an older kernel, but we can be a bit more
    gentle for the benefit of Valgrind or any other software which
    synthesizes the auxv for virtualization purposes.
    
    Reported by:    Paul Floyd <paulf2718@gmail.com>
    MFC after:      1 week
    Reviewed by:    brooks, kib
    Differential Revision:  https://reviews.freebsd.org/D37036
---
 lib/libc/gen/auxv.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/lib/libc/gen/auxv.c b/lib/libc/gen/auxv.c
index af59a2dda90a..2f043f8814cf 100644
--- a/lib/libc/gen/auxv.c
+++ b/lib/libc/gen/auxv.c
@@ -381,15 +381,21 @@ _elf_aux_info(int aux, void *buf, int buflen)
 		break;
 	case AT_USRSTACKBASE:
 		if (buflen == sizeof(u_long)) {
-			*(u_long *)buf = usrstackbase;
-			res = 0;
+			if (usrstackbase != 0) {
+				*(u_long *)buf = usrstackbase;
+				res = 0;
+			} else
+				res = ENOENT;
 		} else
 			res = EINVAL;
 		break;
 	case AT_USRSTACKLIM:
 		if (buflen == sizeof(u_long)) {
-			*(u_long *)buf = usrstacklim;
-			res = 0;
+			if (usrstacklim != 0) {
+				*(u_long *)buf = usrstacklim;
+				res = 0;
+			} else
+				res = ENOENT;
 		} else
 			res = EINVAL;
 		break;