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authorJiri Olsa <jolsa@kernel.org>2016-09-08 10:57:08 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-09-20 23:32:49 +0300
commitdf04abfd181acc276ba6762c8206891ae10ae00d (patch)
tree03afe92ae5ef3e51035ab871e0b29742d11eb0d1
parentf5beeb1851ea6f8cfcf2657f26cb24c0582b4945 (diff)
downloadlinux-df04abfd181acc276ba6762c8206891ae10ae00d.tar.xz
fs/proc/kcore.c: Add bounce buffer for ktext data
We hit hardened usercopy feature check for kernel text access by reading kcore file: usercopy: kernel memory exposure attempt detected from ffffffff8179a01f (<kernel text>) (4065 bytes) kernel BUG at mm/usercopy.c:75! Bypassing this check for kcore by adding bounce buffer for ktext data. Reported-by: Steve Best <sbest@redhat.com> Fixes: f5509cc18daa ("mm: Hardened usercopy") Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/proc/kcore.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index bd3ac9dca252..5c89a07e3d7f 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -509,7 +509,12 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
if (kern_addr_valid(start)) {
unsigned long n;
- n = copy_to_user(buffer, (char *)start, tsz);
+ /*
+ * Using bounce buffer to bypass the
+ * hardened user copy kernel text checks.
+ */
+ memcpy(buf, (char *) start, tsz);
+ n = copy_to_user(buffer, buf, tsz);
/*
* We cannot distinguish between fault on source
* and fault on destination. When this happens