[34/55] xtensa: prevent arbitrary read in ptrace

[Greg KH]

2.6.32-longterm review patch.  If anyone has any objections, please let us know.

------------------

From: Dan Rosenberg <drosenberg@xxxxxxxxxxxxx>

commit 0d0138ebe24b94065580bd2601f8bb7eb6152f56 upstream.

Prevent an arbitrary kernel read.  Check the user pointer with access_ok()
before copying data in.

[akpm@xxxxxxxxxxxxxxxxxxxx: s/EIO/EFAULT/]
Signed-off-by: Dan Rosenberg <drosenberg@xxxxxxxxxxxxx>
Cc: Christian Zankel <chris@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 arch/xtensa/kernel/ptrace.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/arch/xtensa/kernel/ptrace.c
+++ b/arch/xtensa/kernel/ptrace.c
@@ -136,6 +136,9 @@ int ptrace_setxregs(struct task_struct *
 	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);


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