Commit 7bf9b7be authored Dec 16, 2012 by Al Viro Committed by Russell King Dec 20, 2012

ARM: missing ->mmap_sem around find_vma() in swp_emulate.c



find_vma() is *not* safe when somebody else is removing vmas.  Not just
the return value might get bogus just as you are getting it (this instance
doesn't try to dereference the resulting vma), the search itself can get
buggered in rather spectacular ways.  IOW, ->mmap_sem really, really is
not optional here.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

parent dad5451a

arch/arm/kernel/swp_emulate.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -109,10 +109,12 @@ static void set_segfault(struct pt_regs *regs, unsigned long addr)
		{
		siginfo_t info;

		down_read(&current->mm->mmap_sem);
		if (find_vma(current->mm, addr) == NULL)
		info.si_code = SEGV_MAPERR;
		else
		info.si_code = SEGV_ACCERR;
		up_read(&current->mm->mmap_sem);

		info.si_signo = SIGSEGV;
		info.si_errno = 0;