git: 9fcbd4c0d19c - stable/13 - libprocstat: simplify auxv value conversion

The branch stable/13 has been updated by brooks:

URL: https://cgit.FreeBSD.org/src/commit/?id=9fcbd4c0d19cdbfa1fb4711c00c9c9cf84dbefb0

commit 9fcbd4c0d19cdbfa1fb4711c00c9c9cf84dbefb0
Author:     Brooks Davis <brooks@FreeBSD.org>
AuthorDate: 2023-10-26 20:38:41 +0000
Commit:     Brooks Davis <brooks@FreeBSD.org>
CommitDate: 2023-10-26 20:38:41 +0000

    libprocstat: simplify auxv value conversion
    
    Avoid a weird dance through the union and treat all 32-bit values as
    unsigned integers.  This avoids sign extension of flags and userspace
    pointers.
    
    Reviewed by:    markj
    Sponsored by:   DARPA
    Differential Revision:  https://reviews.freebsd.org/D42198
    
    (cherry picked from commit 9735cc0e41825bb9e95d16433d381ffe4c190f38)
---
 lib/libprocstat/libprocstat.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/lib/libprocstat/libprocstat.c b/lib/libprocstat/libprocstat.c
index d27c9f773151..0d7a0bcc2649 100644
--- a/lib/libprocstat/libprocstat.c
+++ b/lib/libprocstat/libprocstat.c
@@ -2417,7 +2417,6 @@ procstat_getauxv32_sysctl(pid_t pid, unsigned int *cntp)
 {
 	Elf_Auxinfo *auxv;
 	Elf32_Auxinfo *auxv32;
-	void *ptr;
 	size_t len;
 	unsigned int i, count;
 	int name[4];
@@ -2451,8 +2450,17 @@ procstat_getauxv32_sysctl(pid_t pid, unsigned int *cntp)
 		 * necessarily true.
 		 */
 		auxv[i].a_type = auxv32[i].a_type;
-		ptr = &auxv32[i].a_un;
-		auxv[i].a_un.a_val = *((uint32_t *)ptr);
+		/*
+		 * Don't sign extend values.  Existing entries are positive
+		 * integers or pointers.  Under freebsd32, programs typically
+		 * have a full [0, 2^32) address space (perhaps minus the last
+		 * page) and treating this as a signed integer would be
+		 * confusing since these are not kernel pointers.
+		 *
+		 * XXX: A more complete translation would be ABI and
+		 * type-aware.
+		 */
+		auxv[i].a_un.a_val = (uint32_t)auxv32[i].a_un.a_val;
 	}
 	*cntp = count;
 out: