s390/dasd: Read cached unit address and LSS in the CCW build path

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The CCW build path (prefix_LRE, the full-track prefix and dso_ras) read the
base address and LSS straight from conf.ned. That buffer is freed and
reallocated by the reload worker (do_reload_device - dasd_eckd_read_conf -
dasd_eckd_clear_conf_data), so a configuration change concurrent with I/O
can free conf.ned while a request is being built.
Use-after-free reported by KASAN in prefix_LRE.

Read the cached copies instead.
The unit address is already kept in uid.real_unit_addr, and the LSS is now
cached in ned_lss. Both are refreshed under the ccwdev lock in
dasd_eckd_generate_uid whenever the configuration is (re)read.
Also fix for prepare for read subsystem data (prssd) users.

Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Link: https://patch.msgid.link/20260805111612.1285190-20-sth@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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This commit is contained in:

Stefan Haberland 2026-08-05 13:16:12 +02:00 • committed by Jens Axboe

parent 04ea1579bc

commit a600051da1

2 changed files with 24 additions and 10 deletions

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26

drivers/s390/block/dasd_eckd.c

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8

drivers/s390/block/dasd_eckd.h

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