[SCSI] NULL pointer dereference in sym53c8xx (bisected)

From: Stratos Psomadakis
Date: Fri Dec 02 2011 - 10:26:37 EST


Hi,

After upstream commit 4e6c82b3614a18740ef63109d58743a359266daf ([SCSI]
fix WARNING: at drivers/scsi/scsi_lib.c:1704), which is also included in
3.0-stable and 3.1-stable kernels, the kernel fails to boot (NULL
pointer dereference in sym53c8xx_slave_destroy).

Bug report at the Gentoo Bugzilla (reported and bisected by Martin von
Gagern). [1] (stack trace [2])

I think that the problem is that (after commit 4e6c82b)
__scsi_remove_device() is called if slave_alloc() in scsi_alloc_sdev()
fails. But __scsi_remove_device() calls slave_destroy(), which (I think)
doesn't make much sense (ie to call slave_destroy() when slave_alloc()
fails).

For sym53c8xx, this results in a NULL pointer dereference (struct
sym_lcb pointer) in slave_destroy().

[1] https://bugs.gentoo.org/show_bug.cgi?id=392567
[2] https://392567.bugs.gentoo.org/attachment.cgi?id=294381

--
Stratos Psomadakis
<psomas@xxxxxxxxxx>


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