The patch titled
Subject: fs/proc/kcore.c: remove check of list iterator against head past the loop body
has been added to the -mm tree. Its filename is
fs-proc-kcorec-remove-check-of-list-iterator-against-head-past-the-loop-body.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/fs-proc-kcorec-remove-check-of-list-iterator-against-head-past-the-loop-body.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/fs-proc-kcorec-remove-check-of-list-iterator-against-head-past-the-loop-body.patch
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------------------------------------------------------
From: Jakob Koschel <jakobkoschel@xxxxxxxxx>
Subject: fs/proc/kcore.c: remove check of list iterator against head past the loop body
When list_for_each_entry() completes the iteration over the whole list
without breaking the loop, the iterator value will be a bogus pointer
computed based on the head element.
While it is safe to use the pointer to determine if it was computed based
on the head element, either with list_entry_is_head() or &pos->member ==
head, using the iterator variable after the loop should be avoided.
In preparation to limit the scope of a list iterator to the list traversal
loop, use a dedicated pointer to point to the found element [1].
Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@xxxxxxxxxxxxxx/ [1]
Link: https://lkml.kernel.org/r/20220331223700.902556-1-jakobkoschel@xxxxxxxxx
Signed-off-by: Jakob Koschel <jakobkoschel@xxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: "Brian Johannesmeyer" <bjohannesmeyer@xxxxxxxxx>
Cc: Cristiano Giuffrida <c.giuffrida@xxxxx>
Cc: "Bos, H.J." <h.j.bos@xxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/kcore.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
--- a/fs/proc/kcore.c~fs-proc-kcorec-remove-check-of-list-iterator-against-head-past-the-loop-body
+++ a/fs/proc/kcore.c
@@ -316,6 +316,7 @@ read_kcore(struct file *file, char __use
size_t page_offline_frozen = 1;
size_t phdrs_len, notes_len;
struct kcore_list *m;
+ struct kcore_list *iter;
size_t tsz;
int nphdr;
unsigned long start;
@@ -479,10 +480,13 @@ read_kcore(struct file *file, char __use
* the previous entry, search for a matching entry.
*/
if (!m || start < m->addr || start >= m->addr + m->size) {
- list_for_each_entry(m, &kclist_head, list) {
- if (start >= m->addr &&
- start < m->addr + m->size)
+ m = NULL;
+ list_for_each_entry(iter, &kclist_head, list) {
+ if (start >= iter->addr &&
+ start < iter->addr + iter->size) {
+ m = iter;
break;
+ }
}
}
@@ -492,12 +496,11 @@ read_kcore(struct file *file, char __use
page_offline_freeze();
}
- if (&m->list == &kclist_head) {
+ if (!m) {
if (clear_user(buffer, tsz)) {
ret = -EFAULT;
goto out;
}
- m = NULL; /* skip the list anchor */
goto skip;
}
_
Patches currently in -mm which might be from jakobkoschel@xxxxxxxxx are
hugetlb-remove-use-of-list-iterator-variable-after-loop.patch
ocfs2-replace-usage-of-found-with-dedicated-list-iterator-variable.patch
ocfs2-remove-usage-of-list-iterator-variable-after-the-loop-body.patch
fs-proc-kcorec-remove-check-of-list-iterator-against-head-past-the-loop-body.patch
rapidio-remove-unnecessary-use-of-list-iterator.patch
