xtensa: prevent arbitrary read in ptrace
commit 0d0138ebe24b94065580bd2601f8bb7eb6152f56 upstream.
Prevent an arbitrary kernel read. Check the user pointer with access_ok()
before copying data in.
[akpm@linux-foundation.org: s/EIO/EFAULT/]
Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/arch/xtensa/kernel/ptrace.c b/arch/xtensa/kernel/ptrace.c
index c72c947..a0d042a 100644
--- a/arch/xtensa/kernel/ptrace.c
+++ b/arch/xtensa/kernel/ptrace.c
@@ -147,6 +147,9 @@
elf_xtregs_t *xtregs = uregs;
int ret = 0;
+ if (!access_ok(VERIFY_READ, uregs, sizeof(elf_xtregs_t)))
+ return -EFAULT;
+
#if XTENSA_HAVE_COPROCESSORS
/* Flush all coprocessors before we overwrite them. */
coprocessor_flush_all(ti);