Messages in this thread | | | Date | Fri, 08 Jul 2011 12:29:15 -0700 | From | Chris Zankel <> | Subject | Re: [Security] [PATCH] xtensa: prevent arbitrary read in ptrace |
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Hi,
I'll try to run a build this weekend and will look if that code builds at all.
Thanks, -Chris
On 7/8/11 11:42 AM, Oleg Nesterov wrote: > 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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