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23 October 2021, 00:29:24 UTC
Revision 89d328f637b9904b6d4c9af73c8a608b8dd4d6f8 authored by Kees Cook on 01 November 2018, 23:17:22 UTC, committed by Kees Cook on 29 November 2018, 21:46:43 UTC 
pstore/ram: Correctly calculate usable PRZ bytes
 
The actual number of bytes stored in a PRZ is smaller than the
bytes requested by platform data, since there is a header on each
PRZ. Additionally, if ECC is enabled, there are trailing bytes used
as well. Normally this mismatch doesn't matter since PRZs are circular
buffers and the leading "overflow" bytes are just thrown away. However, in
the case of a compressed record, this rather badly corrupts the results.

This corruption was visible with "ramoops.mem_size=204800 ramoops.ecc=1".
Any stored crashes would not be uncompressable (producing a pstorefs
"dmesg-*.enc.z" file), and triggering errors at boot:

  [    2.790759] pstore: crypto_comp_decompress failed, ret = -22!

Backporting this depends on commit 70ad35db3321 ("pstore: Convert console
write to use ->write_buf")

Reported-by: Joel Fernandes <joel@joelfernandes.org>
Fixes: b0aad7a99c1d ("pstore: Add compression support to pstore")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
1 parent 1227daa
Raw File
Tip revision: 89d328f637b9904b6d4c9af73c8a608b8dd4d6f8 authored by Kees Cook on 01 November 2018, 23:17:22 UTC
pstore/ram: Correctly calculate usable PRZ bytes
Tip revision: 89d328f
COPYING 
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	SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note

Being under the terms of the GNU General Public License version 2 only,
according with:

	LICENSES/preferred/GPL-2.0

With an explicit syscall exception, as stated at:

	LICENSES/exceptions/Linux-syscall-note

In addition, other licenses may also apply. Please see:

	Documentation/process/license-rules.rst

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