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

[ Upstream commit 9492261ff2460252cf2d8de89cdf854c7e2b28a0 ]

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>

diff --git a/include/linux/generic-radix-tree.h b/include/linux/generic-radix-tree.h
index 107613f..f6cd0f9 100644 (file)
--- a/include/linux/generic-radix-tree.h
+++ b/include/linux/generic-radix-tree.h
@@ -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) &&

diff --git a/lib/generic-radix-tree.c b/lib/generic-radix-tree.c
index f25eb11..7dfa882 100644 (file)
--- a/lib/generic-radix-tree.c
+++ b/lib/generic-radix-tree.c
@@ -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)