Messages in this thread | | | Date | Fri, 8 Jul 2011 20:42:50 +0200 | From | Oleg Nesterov <> | Subject | Re: [Security] [PATCH] xtensa: prevent arbitrary read in ptrace |
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On 07/08, Andrew Morton wrote: > > On Thu, 07 Jul 2011 20:03:54 -0400 > Dan Rosenberg <drosenberg@vsecurity.com> wrote: > > > Prevent an arbitrary kernel read. Check the user pointer with > > access_ok() before copying data in. > > > > Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com> > > Cc: stable@kernel.org > > --- > > arch/xtensa/kernel/ptrace.c | 3 +++ > > 1 files changed, 3 insertions(+), 0 deletions(-) > > > > diff --git a/arch/xtensa/kernel/ptrace.c b/arch/xtensa/kernel/ptrace.c > > index c72c947..ddce75e 100644 > > --- a/arch/xtensa/kernel/ptrace.c > > +++ b/arch/xtensa/kernel/ptrace.c > > @@ -147,6 +147,9 @@ int ptrace_setxregs(struct task_struct *child, void __user *uregs) > > elf_xtregs_t *xtregs = uregs; > > int ret = 0; > > > > + if (!access_ok(VERIFY_READ, uregs, sizeof(elf_xtregs_t))) > > + return -EIO; > > This should be -EFAULT, methinks?
Also, it seems that ptrace_setxregs/ptrace_getxregs could be static?
The patch looks "obviously correct" but I don't understand this code.
Hmm. We don't read/write the XTENSA_HAVE_COPROCESSORS data, but use sizeof(elf_xtregs_t) anyway. This looks a bit strange but I guess this doesn't matter.
Oleg.
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