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] Signed-off-by: Jakob Koschel <jakobkoschel@xxxxxxxxx> --- fs/proc/kcore.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index 982e694aae77..344edcb2addd 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -316,6 +316,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) 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 __user *buffer, size_t buflen, loff_t *fpos) * 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 __user *buffer, size_t buflen, loff_t *fpos) 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; } base-commit: f82da161ea75dc4db21b2499e4b1facd36dab275 -- 2.25.1
