Messages in this thread | | | Date | Sun, 7 Apr 2013 17:18:59 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCH v1 3/9] uretprobes/x86: Hijack return address |
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* Anton Arapov <anton@redhat.com> [2013-04-03 18:00:33]:
> Hijack the return address and replace it with a trampoline address. > > v1 changes: > * use force_sig_info() > * rework and simplify logic > > RFCv5 changes: > * change the fail return code, because orig_ret_vaddr=0 is possible > * style fixup > RFCv2 changes: > * remove ->doomed flag, kill task immediately > > Signed-off-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> --- > arch/x86/include/asm/uprobes.h | 1 + > arch/x86/kernel/uprobes.c | 29 +++++++++++++++++++++++++++++ > 2 files changed, 30 insertions(+) > > diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h > index 8ff8be7..6e51979 100644 > --- a/arch/x86/include/asm/uprobes.h > +++ b/arch/x86/include/asm/uprobes.h > @@ -55,4 +55,5 @@ extern int arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs); > extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk); > extern int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data); > extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs); > +extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs); > #endif /* _ASM_UPROBES_H */ > diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c > index 0ba4cfb..2ed8459 100644 > --- a/arch/x86/kernel/uprobes.c > +++ b/arch/x86/kernel/uprobes.c > @@ -697,3 +697,32 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) > send_sig(SIGTRAP, current, 0); > return ret; > } > + > +unsigned long > +arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs) > +{ > + int rasize, ncopied; > + unsigned long orig_ret_vaddr = 0; /* clear high bits for 32-bit apps */ > + > + rasize = is_ia32_task() ? 4 : 8; > + ncopied = copy_from_user(&orig_ret_vaddr, (void __user *)regs->sp, rasize); > + if (unlikely(ncopied)) > + return -1; > + > + /* check whether address has been already hijacked */ > + if (orig_ret_vaddr == trampoline_vaddr) > + return orig_ret_vaddr; > + > + ncopied = copy_to_user((void __user *)regs->sp, &trampoline_vaddr, rasize); > + if (likely(!ncopied)) > + return orig_ret_vaddr; > + > + if (ncopied != rasize) { > + pr_err("uprobe: return address clobbered: pid=%d, %%sp=%#lx, " > + "%%ip=%#lx\n", current->pid, regs->sp, regs->ip); > + > + force_sig_info(SIGSEGV, SEND_SIG_FORCED, current); > + } > + > + return -1; > +} > -- > 1.8.1.4 >
-- Thanks and Regards Srikar Dronamraju
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