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

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[ Upstream commit 9492261ff2 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kent Overstreet 2021-02-12 20:11:25 -05:00 committed by Greg Kroah-Hartman
parent 96612b6f99
commit ec298b958c
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)