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lib/generic-radix-tree.c: Don't overflow in peek()

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When we started spreading new inode numbers throughout most of the 64
bit inode space, that triggered some corner case bugs, in particular
some integer overflows related to the radix tree code. Oops.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
This commit is contained in:
Kent Overstreet 2021-02-12 20:11:25 -05:00 • committed by Kent Overstreet
parent 0fb5d567f5
commit 9492261ff2
2 changed files with 21 additions and 3 deletions
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7
include/linux/generic-radix-tree.h
View file

@ -38,6 +38,7 @@
#include <asm/page.h>
#include <linux/bug.h>
#include <linux/limits.h>
#include <linux/log2.h>
#include <linux/math.h>
#include <linux/types.h>
@ -184,6 +185,12 @@ void *__genradix_iter_peek(struct genradix_iter *, struct __genradix *, size_t);
static inline void __genradix_iter_advance(struct genradix_iter *iter,
size_t obj_size)
{
if (iter->offset + obj_size < iter->offset) {
iter->offset = SIZE_MAX;
iter->pos = SIZE_MAX;
return;
}
iter->offset += obj_size;
if (!is_power_of_2(obj_size) &&

17
lib/generic-radix-tree.c
View file

@ -166,6 +166,10 @@ void *__genradix_iter_peek(struct genradix_iter *iter,
struct genradix_root *r;
struct genradix_node *n;
unsigned level, i;
if (iter->offset == SIZE_MAX)
return NULL;
restart:
r = READ_ONCE(radix->root);
if (!r)
@ -184,10 +188,17 @@ restart:
(GENRADIX_ARY - 1);
while (!n->children[i]) {
size_t objs_per_ptr = genradix_depth_size(level);
if (iter->offset + objs_per_ptr < iter->offset) {
iter->offset = SIZE_MAX;
iter->pos = SIZE_MAX;
return NULL;
}
i++;
iter->offset = round_down(iter->offset +
genradix_depth_size(level),
genradix_depth_size(level));
iter->offset = round_down(iter->offset + objs_per_ptr,
objs_per_ptr);
iter->pos = (iter->offset >> PAGE_SHIFT) *
objs_per_page;
if (i == GENRADIX_ARY)