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libuutil: deobfuscate internal pointers 

uu_avl and uu_list stored internal next/prev pointers and parent
pointers (unused) obfuscated (byte swapped) to hide them from a long
forgotten leak checker (No one at the 2022 OpenZFS developers meeting
could recall the history.)  This would break on CHERI systems and adds
no obvious value.  Rename the members, use proper types rather than
uintptr_t, and eliminate the related macros.

Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Brooks Davis <brooks.davis@sri.com>
Closes #14126
This commit is contained in:
Brooks Davis 2022-11-03 09:57:05 -07:00 committed by GitHub
parent 211ec1b9fd
commit 27d29946be
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 34 additions and 57 deletions
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31
include/libuutil_impl.h
View File

@ -46,21 +46,6 @@ __attribute__((format(printf, 1, 2), __noreturn__))
void uu_panic(const char *format, ...);
/*
* For debugging purposes, libuutil keeps around linked lists of all uu_lists
* and uu_avls, along with pointers to their parents. These can cause false
* negatives when looking for memory leaks, so we encode the pointers by
* storing them with swapped endianness; this is not perfect, but it's about
* the best we can do without wasting a lot of space.
*/
#ifdef _LP64
#define UU_PTR_ENCODE(ptr) BSWAP_64((uintptr_t)(void *)(ptr))
#else
#define UU_PTR_ENCODE(ptr) BSWAP_32((uintptr_t)(void *)(ptr))
#endif
#define UU_PTR_DECODE(ptr) ((void *)UU_PTR_ENCODE(ptr))
/*
* uu_list structures
*/
@ -80,11 +65,11 @@ struct uu_list_walk {
};
struct uu_list {
uintptr_t ul_next_enc;
uintptr_t ul_prev_enc;
uu_list_t *ul_next;
uu_list_t *ul_prev;
uu_list_pool_t *ul_pool;
uintptr_t ul_parent_enc; /* encoded parent pointer */
void *ul_parent;
size_t ul_offset;
size_t ul_numnodes;
uint8_t ul_debug;
@ -95,8 +80,6 @@ struct uu_list {
uu_list_walk_t ul_null_walk; /* for robust walkers */
};
#define UU_LIST_PTR(ptr) ((uu_list_t *)UU_PTR_DECODE(ptr))
#define UU_LIST_POOL_MAXNAME 64
struct uu_list_pool {
@ -129,11 +112,11 @@ struct uu_avl_walk {
};
struct uu_avl {
uintptr_t ua_next_enc;
uintptr_t ua_prev_enc;
uu_avl_t *ua_next;
uu_avl_t *ua_prev;
uu_avl_pool_t *ua_pool;
uintptr_t ua_parent_enc;
void *ua_parent;
uint8_t ua_debug;
uint8_t ua_index; /* mark for uu_avl_index_ts */
@ -141,8 +124,6 @@ struct uu_avl {
uu_avl_walk_t ua_null_walk;
};
#define UU_AVL_PTR(x) ((uu_avl_t *)UU_PTR_DECODE(x))
#define UU_AVL_POOL_MAXNAME 64
struct uu_avl_pool {

30
lib/libuutil/uu_avl.c
View File

@ -97,8 +97,8 @@ uu_avl_pool_create(const char *name, size_t objsize, size_t nodeoffset,
(void) pthread_mutex_init(&pp->uap_lock, NULL);
pp->uap_null_avl.ua_next_enc = UU_PTR_ENCODE(&pp->uap_null_avl);
pp->uap_null_avl.ua_prev_enc = UU_PTR_ENCODE(&pp->uap_null_avl);
pp->uap_null_avl.ua_next = &pp->uap_null_avl;
pp->uap_null_avl.ua_prev = &pp->uap_null_avl;
(void) pthread_mutex_lock(&uu_apool_list_lock);
pp->uap_next = next = &uu_null_apool;
@ -114,10 +114,8 @@ void
uu_avl_pool_destroy(uu_avl_pool_t *pp)
{
if (pp->uap_debug) {
if (pp->uap_null_avl.ua_next_enc !=
UU_PTR_ENCODE(&pp->uap_null_avl) ||
pp->uap_null_avl.ua_prev_enc !=
UU_PTR_ENCODE(&pp->uap_null_avl)) {
if (pp->uap_null_avl.ua_next != &pp->uap_null_avl ||
pp->uap_null_avl.ua_prev != &pp->uap_null_avl) {
uu_panic("uu_avl_pool_destroy: Pool \"%.*s\" (%p) has "
"outstanding avls, or is corrupt.\n",
(int)sizeof (pp->uap_name), pp->uap_name,
@ -224,7 +222,7 @@ uu_avl_create(uu_avl_pool_t *pp, void *parent, uint32_t flags)
}
ap->ua_pool = pp;
ap->ua_parent_enc = UU_PTR_ENCODE(parent);
ap->ua_parent = parent;
ap->ua_debug = pp->uap_debug || (flags & UU_AVL_DEBUG);
ap->ua_index = (pp->uap_last_index = INDEX_NEXT(pp->uap_last_index));
@ -236,11 +234,11 @@ uu_avl_create(uu_avl_pool_t *pp, void *parent, uint32_t flags)
(void) pthread_mutex_lock(&pp->uap_lock);
next = &pp->uap_null_avl;
prev = UU_PTR_DECODE(next->ua_prev_enc);
ap->ua_next_enc = UU_PTR_ENCODE(next);
ap->ua_prev_enc = UU_PTR_ENCODE(prev);
next->ua_prev_enc = UU_PTR_ENCODE(ap);
prev->ua_next_enc = UU_PTR_ENCODE(ap);
prev = next->ua_prev;
ap->ua_next = next;
ap->ua_prev = prev;
next->ua_prev = ap;
prev->ua_next = ap;
(void) pthread_mutex_unlock(&pp->uap_lock);
return (ap);
@ -263,11 +261,11 @@ uu_avl_destroy(uu_avl_t *ap)
}
}
(void) pthread_mutex_lock(&pp->uap_lock);
UU_AVL_PTR(ap->ua_next_enc)->ua_prev_enc = ap->ua_prev_enc;
UU_AVL_PTR(ap->ua_prev_enc)->ua_next_enc = ap->ua_next_enc;
ap->ua_next->ua_prev = ap->ua_prev;
ap->ua_prev->ua_next = ap->ua_next;
(void) pthread_mutex_unlock(&pp->uap_lock);
ap->ua_prev_enc = UU_PTR_ENCODE(NULL);
ap->ua_next_enc = UU_PTR_ENCODE(NULL);
ap->ua_prev = NULL;
ap->ua_next = NULL;
ap->ua_pool = NULL;
avl_destroy(&ap->ua_tree);

30
lib/libuutil/uu_list.c
View File

@ -93,8 +93,8 @@ uu_list_pool_create(const char *name, size_t objsize,
(void) pthread_mutex_init(&pp->ulp_lock, NULL);
pp->ulp_null_list.ul_next_enc = UU_PTR_ENCODE(&pp->ulp_null_list);
pp->ulp_null_list.ul_prev_enc = UU_PTR_ENCODE(&pp->ulp_null_list);
pp->ulp_null_list.ul_next = &pp->ulp_null_list;
pp->ulp_null_list.ul_prev = &pp->ulp_null_list;
(void) pthread_mutex_lock(&uu_lpool_list_lock);
pp->ulp_next = next = &uu_null_lpool;
@ -110,10 +110,8 @@ void
uu_list_pool_destroy(uu_list_pool_t *pp)
{
if (pp->ulp_debug) {
if (pp->ulp_null_list.ul_next_enc !=
UU_PTR_ENCODE(&pp->ulp_null_list) ||
pp->ulp_null_list.ul_prev_enc !=
UU_PTR_ENCODE(&pp->ulp_null_list)) {
if (pp->ulp_null_list.ul_next != &pp->ulp_null_list ||
pp->ulp_null_list.ul_prev != &pp->ulp_null_list) {
uu_panic("uu_list_pool_destroy: Pool \"%.*s\" (%p) has "
"outstanding lists, or is corrupt.\n",
(int)sizeof (pp->ulp_name), pp->ulp_name,
@ -202,7 +200,7 @@ uu_list_create(uu_list_pool_t *pp, void *parent, uint32_t flags)
}
lp->ul_pool = pp;
lp->ul_parent_enc = UU_PTR_ENCODE(parent);
lp->ul_parent = parent;
lp->ul_offset = pp->ulp_nodeoffset;
lp->ul_debug = pp->ulp_debug || (flags & UU_LIST_DEBUG);
lp->ul_sorted = (flags & UU_LIST_SORTED);
@ -217,11 +215,11 @@ uu_list_create(uu_list_pool_t *pp, void *parent, uint32_t flags)
(void) pthread_mutex_lock(&pp->ulp_lock);
next = &pp->ulp_null_list;
prev = UU_PTR_DECODE(next->ul_prev_enc);
lp->ul_next_enc = UU_PTR_ENCODE(next);
lp->ul_prev_enc = UU_PTR_ENCODE(prev);
next->ul_prev_enc = UU_PTR_ENCODE(lp);
prev->ul_next_enc = UU_PTR_ENCODE(lp);
prev = next->ul_prev;
lp->ul_next = next;
lp->ul_prev = prev;
next->ul_prev = lp;
prev->ul_next = lp;
(void) pthread_mutex_unlock(&pp->ulp_lock);
return (lp);
@ -250,11 +248,11 @@ uu_list_destroy(uu_list_t *lp)
}
(void) pthread_mutex_lock(&pp->ulp_lock);
UU_LIST_PTR(lp->ul_next_enc)->ul_prev_enc = lp->ul_prev_enc;
UU_LIST_PTR(lp->ul_prev_enc)->ul_next_enc = lp->ul_next_enc;
lp->ul_next->ul_prev = lp->ul_prev;
lp->ul_prev->ul_next = lp->ul_next;
(void) pthread_mutex_unlock(&pp->ulp_lock);
lp->ul_prev_enc = UU_PTR_ENCODE(NULL);
lp->ul_next_enc = UU_PTR_ENCODE(NULL);
lp->ul_prev = NULL;
lp->ul_next = NULL;
lp->ul_pool = NULL;
uu_free(lp);
}