git: 69e2004d8434 - stable/13 - kern_sysctl: Make name2oid() non-destructive to the name

[Zhenlei Huang]

The branch stable/13 has been updated by zlei:

URL: 
https://cgit.FreeBSD.org/src/commit/?id=69e2004d843452bffdebdf164ab5346b1b81a9e6

commit 69e2004d843452bffdebdf164ab5346b1b81a9e6
Author:     Alexander Motin <m...@freebsd.org>
AuthorDate: 2023-09-23 16:13:46 +0000
Commit:     Zhenlei Huang <z...@freebsd.org>
CommitDate: 2025-01-23 11:09:34 +0000

    kern_sysctl: Make name2oid() non-destructive to the name
    
    It is not the first time I see it panicking while trying to modify
    const memory.  Lets make it safer and easier to use.  While there,
    mark few functions using it also const.
    
    MFC after:      10 days
    
    (cherry picked from commit f80babf906b7be51b2a031ef26525893c7bf4e31)
    (cherry picked from commit 1a1a1728e0bec6e5b978e6c5c7433ca91596b389)
---
 sys/kern/kern_sysctl.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index aa9d271f3bd2..a19f3a5ab27b 100644
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -125,6 +125,7 @@ static int  sysctl_remove_oid_locked(struct sysctl_oid 
*oidp, int del,
                    int recurse);
 static int     sysctl_old_kernel(struct sysctl_req *, const void *, size_t);
 static int     sysctl_new_kernel(struct sysctl_req *, void *, size_t);
+static int     name2oid(const char *, int *, int *, struct sysctl_oid **);
 
 static struct sysctl_oid *
 sysctl_find_oidname(const char *name, struct sysctl_oid_list *list)
@@ -140,6 +141,21 @@ sysctl_find_oidname(const char *name, struct 
sysctl_oid_list *list)
        return (NULL);
 }
 
+static struct sysctl_oid *
+sysctl_find_oidnamelen(const char *name, size_t len,
+    struct sysctl_oid_list *list)
+{
+       struct sysctl_oid *oidp;
+
+       SYSCTL_ASSERT_LOCKED();
+       SYSCTL_FOREACH(oidp, list) {
+               if (strncmp(oidp->oid_name, name, len) == 0 &&
+                   oidp->oid_name[len] == '\0')
+                       return (oidp);
+       }
+       return (NULL);
+}
+
 /*
  * Initialization of the MIB tree.
  *
@@ -1319,21 +1335,26 @@ static SYSCTL_NODE(_sysctl, CTL_SYSCTL_NEXTNOSKIP, 
nextnoskip, CTLFLAG_RD |
     CTLFLAG_MPSAFE | CTLFLAG_CAPRD, sysctl_sysctl_next, "");
 
 static int
-name2oid(char *name, int *oid, int *len, struct sysctl_oid **oidpp)
+name2oid(const char *name, int *oid, int *len, struct sysctl_oid **oidpp)
 {
        struct sysctl_oid *oidp;
        struct sysctl_oid_list *lsp = &sysctl__children;
+       const char *n;
 
        SYSCTL_ASSERT_LOCKED();
 
        for (*len = 0; *len < CTL_MAXNAME;) {
-               oidp = sysctl_find_oidname(strsep(&name, "."), lsp);
+               n = strchrnul(name, '.');
+               oidp = sysctl_find_oidnamelen(name, n - name, lsp);
                if (oidp == NULL)
                        return (ENOENT);
                *oid++ = oidp->oid_number;
                (*len)++;
 
-               if (name == NULL || *name == '\0') {
+               name = n;
+               if (*name == '.')
+                       name++;
+               if (*name == '\0') {
                        if (oidpp)
                                *oidpp = oidp;
                        return (0);
@@ -2909,7 +2930,7 @@ db_show_sysctl_all(int *oid, size_t len, int flags)
  * Show a sysctl by its user facing string
  */
 static int
-db_sysctlbyname(char *name, int flags)
+db_sysctlbyname(const char *name, int flags)
 {
        struct sysctl_oid *oidp;
        int oid[CTL_MAXNAME];