linux/lib/generic-radix-tree.c
Eric Biggers 3c52b0af05 lib/generic-radix-tree.c: add kmemleak annotations
Kmemleak is falsely reporting a leak of the slab allocation in
sctp_stream_init_ext():

  BUG: memory leak
  unreferenced object 0xffff8881114f5d80 (size 96):
   comm "syz-executor934", pid 7160, jiffies 4294993058 (age 31.950s)
   hex dump (first 32 bytes):
     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
   backtrace:
     [<00000000ce7a1326>] kmemleak_alloc_recursive  include/linux/kmemleak.h:55 [inline]
     [<00000000ce7a1326>] slab_post_alloc_hook mm/slab.h:439 [inline]
     [<00000000ce7a1326>] slab_alloc mm/slab.c:3326 [inline]
     [<00000000ce7a1326>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
     [<000000007abb7ac9>] kmalloc include/linux/slab.h:547 [inline]
     [<000000007abb7ac9>] kzalloc include/linux/slab.h:742 [inline]
     [<000000007abb7ac9>] sctp_stream_init_ext+0x2b/0xa0  net/sctp/stream.c:157
     [<0000000048ecb9c1>] sctp_sendmsg_to_asoc+0x946/0xa00  net/sctp/socket.c:1882
     [<000000004483ca2b>] sctp_sendmsg+0x2a8/0x990 net/sctp/socket.c:2102
     [...]

But it's freed later.  Kmemleak misses the allocation because its
pointer is stored in the generic radix tree sctp_stream::out, and the
generic radix tree uses raw pages which aren't tracked by kmemleak.

Fix this by adding the kmemleak hooks to the generic radix tree code.

Link: http://lkml.kernel.org/r/20191004065039.727564-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reported-by: <syzbot+7f3b6b106be8dcdcdeec@syzkaller.appspotmail.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Vlad Yasevich <vyasevich@gmail.com>
Cc: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-10-14 15:04:00 -07:00

238 lines
5.3 KiB
C

#include <linux/export.h>
#include <linux/generic-radix-tree.h>
#include <linux/gfp.h>
#include <linux/kmemleak.h>
#define GENRADIX_ARY (PAGE_SIZE / sizeof(struct genradix_node *))
#define GENRADIX_ARY_SHIFT ilog2(GENRADIX_ARY)
struct genradix_node {
union {
/* Interior node: */
struct genradix_node *children[GENRADIX_ARY];
/* Leaf: */
u8 data[PAGE_SIZE];
};
};
static inline int genradix_depth_shift(unsigned depth)
{
return PAGE_SHIFT + GENRADIX_ARY_SHIFT * depth;
}
/*
* Returns size (of data, in bytes) that a tree of a given depth holds:
*/
static inline size_t genradix_depth_size(unsigned depth)
{
return 1UL << genradix_depth_shift(depth);
}
/* depth that's needed for a genradix that can address up to ULONG_MAX: */
#define GENRADIX_MAX_DEPTH \
DIV_ROUND_UP(BITS_PER_LONG - PAGE_SHIFT, GENRADIX_ARY_SHIFT)
#define GENRADIX_DEPTH_MASK \
((unsigned long) (roundup_pow_of_two(GENRADIX_MAX_DEPTH + 1) - 1))
static inline unsigned genradix_root_to_depth(struct genradix_root *r)
{
return (unsigned long) r & GENRADIX_DEPTH_MASK;
}
static inline struct genradix_node *genradix_root_to_node(struct genradix_root *r)
{
return (void *) ((unsigned long) r & ~GENRADIX_DEPTH_MASK);
}
/*
* Returns pointer to the specified byte @offset within @radix, or NULL if not
* allocated
*/
void *__genradix_ptr(struct __genradix *radix, size_t offset)
{
struct genradix_root *r = READ_ONCE(radix->root);
struct genradix_node *n = genradix_root_to_node(r);
unsigned level = genradix_root_to_depth(r);
if (ilog2(offset) >= genradix_depth_shift(level))
return NULL;
while (1) {
if (!n)
return NULL;
if (!level)
break;
level--;
n = n->children[offset >> genradix_depth_shift(level)];
offset &= genradix_depth_size(level) - 1;
}
return &n->data[offset];
}
EXPORT_SYMBOL(__genradix_ptr);
static inline struct genradix_node *genradix_alloc_node(gfp_t gfp_mask)
{
struct genradix_node *node;
node = (struct genradix_node *)__get_free_page(gfp_mask|__GFP_ZERO);
/*
* We're using pages (not slab allocations) directly for kernel data
* structures, so we need to explicitly inform kmemleak of them in order
* to avoid false positive memory leak reports.
*/
kmemleak_alloc(node, PAGE_SIZE, 1, gfp_mask);
return node;
}
static inline void genradix_free_node(struct genradix_node *node)
{
kmemleak_free(node);
free_page((unsigned long)node);
}
/*
* Returns pointer to the specified byte @offset within @radix, allocating it if
* necessary - newly allocated slots are always zeroed out:
*/
void *__genradix_ptr_alloc(struct __genradix *radix, size_t offset,
gfp_t gfp_mask)
{
struct genradix_root *v = READ_ONCE(radix->root);
struct genradix_node *n, *new_node = NULL;
unsigned level;
/* Increase tree depth if necessary: */
while (1) {
struct genradix_root *r = v, *new_root;
n = genradix_root_to_node(r);
level = genradix_root_to_depth(r);
if (n && ilog2(offset) < genradix_depth_shift(level))
break;
if (!new_node) {
new_node = genradix_alloc_node(gfp_mask);
if (!new_node)
return NULL;
}
new_node->children[0] = n;
new_root = ((struct genradix_root *)
((unsigned long) new_node | (n ? level + 1 : 0)));
if ((v = cmpxchg_release(&radix->root, r, new_root)) == r) {
v = new_root;
new_node = NULL;
}
}
while (level--) {
struct genradix_node **p =
&n->children[offset >> genradix_depth_shift(level)];
offset &= genradix_depth_size(level) - 1;
n = READ_ONCE(*p);
if (!n) {
if (!new_node) {
new_node = genradix_alloc_node(gfp_mask);
if (!new_node)
return NULL;
}
if (!(n = cmpxchg_release(p, NULL, new_node)))
swap(n, new_node);
}
}
if (new_node)
genradix_free_node(new_node);
return &n->data[offset];
}
EXPORT_SYMBOL(__genradix_ptr_alloc);
void *__genradix_iter_peek(struct genradix_iter *iter,
struct __genradix *radix,
size_t objs_per_page)
{
struct genradix_root *r;
struct genradix_node *n;
unsigned level, i;
restart:
r = READ_ONCE(radix->root);
if (!r)
return NULL;
n = genradix_root_to_node(r);
level = genradix_root_to_depth(r);
if (ilog2(iter->offset) >= genradix_depth_shift(level))
return NULL;
while (level) {
level--;
i = (iter->offset >> genradix_depth_shift(level)) &
(GENRADIX_ARY - 1);
while (!n->children[i]) {
i++;
iter->offset = round_down(iter->offset +
genradix_depth_size(level),
genradix_depth_size(level));
iter->pos = (iter->offset >> PAGE_SHIFT) *
objs_per_page;
if (i == GENRADIX_ARY)
goto restart;
}
n = n->children[i];
}
return &n->data[iter->offset & (PAGE_SIZE - 1)];
}
EXPORT_SYMBOL(__genradix_iter_peek);
static void genradix_free_recurse(struct genradix_node *n, unsigned level)
{
if (level) {
unsigned i;
for (i = 0; i < GENRADIX_ARY; i++)
if (n->children[i])
genradix_free_recurse(n->children[i], level - 1);
}
genradix_free_node(n);
}
int __genradix_prealloc(struct __genradix *radix, size_t size,
gfp_t gfp_mask)
{
size_t offset;
for (offset = 0; offset < size; offset += PAGE_SIZE)
if (!__genradix_ptr_alloc(radix, offset, gfp_mask))
return -ENOMEM;
return 0;
}
EXPORT_SYMBOL(__genradix_prealloc);
void __genradix_free(struct __genradix *radix)
{
struct genradix_root *r = xchg(&radix->root, NULL);
genradix_free_recurse(genradix_root_to_node(r),
genradix_root_to_depth(r));
}
EXPORT_SYMBOL(__genradix_free);