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[PATCH 2/6] xfs_db: write command broken on 64 bit values

To: xfs@xxxxxxxxxxx
Subject: [PATCH 2/6] xfs_db: write command broken on 64 bit values
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Fri, 4 Jul 2014 15:57:11 +1000
Cc: arekm@xxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1404453435-1915-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1404453435-1915-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

convert_args() has problesm with 64 bit fields because it tries to
shift them by 64 bits. The result of doing so is undefined by the C
standard, and so results in the unexpected behaviour of the result
being being the original value unchanged rather than 0. Hence you
can't write 64 bit fields because the code thinks that all values
other than 0 are out of range.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
 db/write.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/db/write.c b/db/write.c
index ca8bd0f..0157a44 100644
--- a/db/write.c
+++ b/db/write.c
@@ -565,7 +565,7 @@ convert_arg(
                return NULL;
 
        /* Does the value fit into the range of the destination bitfield? */
-       if ((val >> bit_length) > 0)
+       if (bit_length < 64 && (val >> bit_length) > 0)
                return NULL;
        /*
         * If the length of the field is not a multiple of a byte, push
-- 
2.0.0

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