linux-kernel - [PATCH 2/2] asmlinkage_protect sys_io

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Date:	Thu, 10 Apr 2008 15:38:45 -0700 (PDT)
From:	Roland McGrath <roland@...hat.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] asmlinkage_protect sys_io_getevents

Use asmlinkage_protect in sys_io_getevents, because GCC for i386 with
CONFIG_FRAME_POINTER=n can decide to clobber an argument word on the
stack, i.e. the user struct pt_regs.  Here the problem is not a tail
call, but just the compiler's use of the stack when it inlines and
optimizes the body of the called function.  This seems to avoid it.

Signed-off-by: Roland McGrath <roland@...hat.com>
---
 fs/aio.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 6af9219..60a4cd4 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1790,6 +1790,7 @@ asmlinkage long sys_io_getevents(aio_context_t ctx_id,
 		put_ioctx(ioctx);
 	}
 
+	asmlinkage_protect(5, ret, ctx_id, min_nr, nr, events, timeout);
 	return ret;
 }
 
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