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Date: Sun, 16 Sep 2012 19:52:42 +0200 From: Oleg Nesterov <oleg@...hat.com> To: Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>, Srikar Dronamraju <srikar@...ux.vnet.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>, Anton Arapov <anton@...hat.com>, Sebastian Andrzej Siewior <bigeasy@...utronix.de>, linux-kernel@...r.kernel.org Subject: [PATCH 1/3] uprobes: Change write_opcode() to use FOLL_FORCE write_opcode()->get_user_pages() needs FOLL_FORCE to ensure we can read the page even if the probed task did mprotect(PROT_NONE) after uprobe_register(). Without FOLL_WRITE, FOLL_FORCE doesn't have any side effect but allows to read the !VM_READ memory. Otherwiese the subsequent uprobe_unregister()->set_orig_insn() fails and we leak "int3". If that task does mprotect(PROT_READ | EXEC) and execute the probed insn later it will be killed. Note: in fact this is also needed for _register, see the next patch. Signed-off-by: Oleg Nesterov <oleg@...hat.com> --- kernel/events/uprobes.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 14c2e99..fa1579a 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -221,7 +221,7 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, retry: /* Read the page with vaddr into memory */ - ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma); + ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma); if (ret <= 0) return ret; -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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