Re: ubifs: error unwinding trouble

From: Adrian Hunter
Date: Fri Jul 24 2009 - 06:49:02 EST


Daniel Mack wrote:
On a recent git kernel, the error unwinding for UBIFS seems to have some
problem, most probably a double-free or something similar.

When UBI is pointed to the right mtd partition (using command line
arguments) , everything is fine. But when it's (accidentionally) set to
some very small mtd, the attach process fails. Which wouldn't be a bad
thing by itself, but it somehow messes up the slub/slab allocators then
which causes very strange memory corruption effects - see the backtrace
below.

The Ooops itself is unreleated to UBI, but it does not occur when UBI
succeeds in attaching the volume.

Any idea? I searched for awhile but couldn't see anything obvious.

Looks like a double free of the eba_tbl

This might help:

diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index 0f2034c..e4d9ef0 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -1254,6 +1254,7 @@ out_free:
if (!ubi->volumes[i])
continue;
kfree(ubi->volumes[i]->eba_tbl);
+ ubi->volumes[i]->eba_tbl = NULL;
}
return err;
}

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