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stand: module: unlink the entire tail when dependencies fail to load

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Assume you have loader configured to load linux64, which has a
dependency on both linux_common and mqueuefs but neither the kernel
nor kernel config in question have the mqueuefs module included.

When the load command for linux64 fails to find mqueuefs, it will
free both linux64 and linux_common as they were loaded first, but only
linux64 gets removed from the module list.  As a result, future
traversals hit an easy use-after-free with linux_common.

Fix it so that we unlink the entire tail of the list.  Anything after
the initially loaded module is, by definition, a dependency on the
loaded module while we're still in the load command, so we can just
discard the entire tail.  If linux_common were loaded before linux64, it
should not move to a position during this load where it would suddenly
be missing from the view presented to the kernel.

Reported by:	philip
Reviewed by:	imp, philip, tsoome
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D45731
This commit is contained in:
Kyle Evans 2024-06-25 15:31:50 -05:00
parent 7d6932d20a
commit 3da568710f
1 changed files with 26 additions and 5 deletions
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31
stand/common/module.c
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@ -64,6 +64,7 @@ static char *mod_searchmodule(char *name, struct mod_depend *verinfo);
static char * mod_searchmodule_pnpinfo(const char *bus, const char *pnpinfo);
static void file_insert_tail(struct preloaded_file *mp);
static void file_remove(struct preloaded_file *fp);
static void file_remove_tail(struct preloaded_file *fp);
struct file_metadata* metadata_next(struct file_metadata *base_mp, int type);
static void moduledir_readhints(struct moduledir *mdp);
static void moduledir_rebuild(void);
@ -876,7 +877,7 @@ mod_loadkld(const char *kldname, int argc, char *argv[])
file_insert_tail(fp); /* Add to the list of loaded files */
if (file_load_dependencies(fp) != 0) {
err = ENOENT;
file_remove(fp);
file_remove_tail(fp);
loadaddr = loadaddr_saved;
fp = NULL;
break;
@ -1637,25 +1638,45 @@ file_insert_tail(struct preloaded_file *fp)
* Remove module from the chain
*/
static void
file_remove(struct preloaded_file *fp)
file_remove_impl(struct preloaded_file *fp, bool keep_tail)
{
struct preloaded_file *cm;
struct preloaded_file *cm, *next;
if (preloaded_files == NULL)
return;
if (keep_tail)
next = fp->f_next;
else
next = NULL;
if (preloaded_files == fp) {
preloaded_files = fp->f_next;
preloaded_files = next;
return;
}
for (cm = preloaded_files; cm->f_next != NULL; cm = cm->f_next) {
if (cm->f_next == fp) {
cm->f_next = fp->f_next;
cm->f_next = next;
return;
}
}
}
static void
file_remove(struct preloaded_file *fp)
{
file_remove_impl(fp, true);
}
static void
file_remove_tail(struct preloaded_file *fp)
{
file_remove_impl(fp, false);
}
static char *
moduledir_fullpath(struct moduledir *mdp, const char *fname)
{