From a1b3d2f217cf51505858c5c160abef96c3e91721 Mon Sep 17 00:00:00 2001 From: Dominique Martinet Date: Thu, 20 Sep 2018 12:22:35 -0700 Subject: [PATCH] fs/proc/kcore.c: fix invalid memory access in multi-page read optimization The 'm' kcore_list item could point to kclist_head, and it is incorrect to look at m->addr / m->size in this case. There is no choice but to run through the list of entries for every address if we did not find any entry in the previous iteration Reset 'm' to NULL in that case at Omar Sandoval's suggestion. [akpm@linux-foundation.org: add comment] Link: http://lkml.kernel.org/r/1536100702-28706-1-git-send-email-asmadeus@codewreck.org Fixes: bf991c2231117 ("proc/kcore: optimize multiple page reads") Signed-off-by: Dominique Martinet Reviewed-by: Andrew Morton Cc: Omar Sandoval Cc: Alexey Dobriyan Cc: Eric Biederman Cc: James Morse Cc: Bhupesh Sharma Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- fs/proc/kcore.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index ad72261ee3fe..d297fe4472a9 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -464,6 +464,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) ret = -EFAULT; goto out; } + m = NULL; /* skip the list anchor */ } else if (m->type == KCORE_VMALLOC) { vread(buf, (char *)start, tsz); /* we have to zero-fill user buffer even if no read */