kernel/linux.git/arch/powerpc/platforms/powernv, branch linux-4.4.y

powerpc/powernv: add missing of_node_put

2022-01-27T07:46:18+00:00

[ Upstream commit 7d405a939ca960162eb30c1475759cb2fdf38f8c ] for_each_compatible_node performs an of_node_get on each iteration, so a break out of the loop requires an of_node_put. A simplified version of the semantic patch that fixes this problem is as follows (http://coccinelle.lip6.fr): // @@ local idexpression n; expression e; @@ for_each_compatible_node(n,...) { ... ( of_node_put(n); | e = n | + of_node_put(n); ? break; ) ... } ... when != n // Signed-off-by: Julia Lawall Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/1448051604-25256-4-git-send-email-Julia.Lawall@lip6.fr Signed-off-by: Sasha Levin

powerpc/64s: flush L1D after user accesses

2020-11-22T08:56:58+00:00

commit 9a32a7e78bd0cd9a9b6332cbdc345ee5ffd0c5de upstream. IBM Power9 processors can speculatively operate on data in the L1 cache before it has been completely validated, via a way-prediction mechanism. It is not possible for an attacker to determine the contents of impermissible memory using this method, since these systems implement a combination of hardware and software security measures to prevent scenarios where protected data could be leaked. However these measures don't address the scenario where an attacker induces the operating system to speculatively execute instructions using data that the attacker controls. This can be used for example to speculatively bypass "kernel user access prevention" techniques, as discovered by Anthony Steinhauser of Google's Safeside Project. This is not an attack by itself, but there is a possibility it could be used in conjunction with side-channels or other weaknesses in the privileged code to construct an attack. This issue can be mitigated by flushing the L1 cache between privilege boundaries of concern. This patch flushes the L1 cache after user accesses. This is part of the fix for CVE-2020-4788. Signed-off-by: Nicholas Piggin Signed-off-by: Daniel Axtens Signed-off-by: Greg Kroah-Hartman

powerpc/64s: flush L1D on kernel entry

2020-11-22T08:56:57+00:00

commit f79643787e0a0762d2409b7b8334e83f22d85695 upstream. IBM Power9 processors can speculatively operate on data in the L1 cache before it has been completely validated, via a way-prediction mechanism. It is not possible for an attacker to determine the contents of impermissible memory using this method, since these systems implement a combination of hardware and software security measures to prevent scenarios where protected data could be leaked. However these measures don't address the scenario where an attacker induces the operating system to speculatively execute instructions using data that the attacker controls. This can be used for example to speculatively bypass "kernel user access prevention" techniques, as discovered by Anthony Steinhauser of Google's Safeside Project. This is not an attack by itself, but there is a possibility it could be used in conjunction with side-channels or other weaknesses in the privileged code to construct an attack. This issue can be mitigated by flushing the L1 cache between privilege boundaries of concern. This patch flushes the L1 cache on kernel entry. This is part of the fix for CVE-2020-4788. Signed-off-by: Nicholas Piggin Signed-off-by: Daniel Axtens Signed-off-by: Greg Kroah-Hartman

powerpc/powernv/elog: Fix race while processing OPAL error log event.

2020-11-10T09:22:16+00:00

commit aea948bb80b478ddc2448f7359d574387521a52d upstream. Every error log reported by OPAL is exported to userspace through a sysfs interface and notified using kobject_uevent(). The userspace daemon (opal_errd) then reads the error log and acknowledges the error log is saved safely to disk. Once acknowledged the kernel removes the respective sysfs file entry causing respective resources to be released including kobject. However it's possible the userspace daemon may already be scanning elog entries when a new sysfs elog entry is created by the kernel. User daemon may read this new entry and ack it even before kernel can notify userspace about it through kobject_uevent() call. If that happens then we have a potential race between elog_ack_store->kobject_put() and kobject_uevent which can lead to use-after-free of a kernfs object resulting in a kernel crash. eg: BUG: Unable to handle kernel data access on read at 0x6b6b6b6b6b6b6bfb Faulting instruction address: 0xc0000000008ff2a0 Oops: Kernel access of bad area, sig: 11 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV CPU: 27 PID: 805 Comm: irq/29-opal-elo Not tainted 5.9.0-rc2-gcc-8.2.0-00214-g6f56a67bcbb5-dirty #363 ... NIP kobject_uevent_env+0xa0/0x910 LR elog_event+0x1f4/0x2d0 Call Trace: 0x5deadbeef0000122 (unreliable) elog_event+0x1f4/0x2d0 irq_thread_fn+0x4c/0xc0 irq_thread+0x1c0/0x2b0 kthread+0x1c4/0x1d0 ret_from_kernel_thread+0x5c/0x6c This patch fixes this race by protecting the sysfs file creation/notification by holding a reference count on kobject until we safely send kobject_uevent(). The function create_elog_obj() returns the elog object which if used by caller function will end up in use-after-free problem again. However, the return value of create_elog_obj() function isn't being used today and there is no need as well. Hence change it to return void to make this fix complete. Fixes: 774fea1a38c6 ("powerpc/powernv: Read OPAL error log and export it through sysfs") Cc: stable@vger.kernel.org # v3.15+ Reported-by: Oliver O'Halloran Signed-off-by: Mahesh Salgaonkar Signed-off-by: Aneesh Kumar K.V Reviewed-by: Oliver O'Halloran Reviewed-by: Vasant Hegde [mpe: Rework the logic to use a single return, reword comments, add oops] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201006122051.190176-1-mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman

powerpc/powernv/smp: Fix spurious DBG() warning

2020-11-10T09:22:12+00:00

[ Upstream commit f6bac19cf65c5be21d14a0c9684c8f560f2096dd ] When building with W=1 we get the following warning: arch/powerpc/platforms/powernv/smp.c: In function ‘pnv_smp_cpu_kill_self’: arch/powerpc/platforms/powernv/smp.c:276:16: error: suggest braces around empty body in an ‘if’ statement [-Werror=empty-body] 276 | cpu, srr1); | ^ cc1: all warnings being treated as errors The full context is this block: if (srr1 && !generic_check_cpu_restart(cpu)) DBG("CPU%d Unexpected exit while offline srr1=%lx!\n", cpu, srr1); When building with DEBUG undefined DBG() expands to nothing and GCC emits the warning due to the lack of braces around an empty statement. Signed-off-by: Oliver O'Halloran Reviewed-by: Joel Stanley Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200804005410.146094-2-oohall@gmail.com Signed-off-by: Sasha Levin

powerpc/powernv/opal-dump : Use IRQ_HANDLED instead of numbers in interrupt handler

2020-11-10T09:22:11+00:00

commit b29336c0e1785a28bc40a9fd47c2321671e9792e upstream. Fixes: 8034f715f ("powernv/opal-dump: Convert to irq domain") Converts all the return explicit number to a more proper IRQ_HANDLED, which looks proper incase of interrupt handler returning case. Here, It also removes error message like "nobody cared" which was getting unveiled while returning -1 or 0 from handler. Signed-off-by: Mukesh Ojha Reviewed-by: Vasant Hegde Signed-off-by: Michael Ellerman Cc: Kamal Mostafa Signed-off-by: Greg Kroah-Hartman

powerpc/powernv/dump: Fix race while processing OPAL dump

2020-10-29T08:03:08+00:00

[ Upstream commit 0a43ae3e2beb77e3481d812834d33abe270768ab ] Every dump reported by OPAL is exported to userspace through a sysfs interface and notified using kobject_uevent(). The userspace daemon (opal_errd) then reads the dump and acknowledges that the dump is saved safely to disk. Once acknowledged the kernel removes the respective sysfs file entry causing respective resources to be released including kobject. However it's possible the userspace daemon may already be scanning dump entries when a new sysfs dump entry is created by the kernel. User daemon may read this new entry and ack it even before kernel can notify userspace about it through kobject_uevent() call. If that happens then we have a potential race between dump_ack_store->kobject_put() and kobject_uevent which can lead to use-after-free of a kernfs object resulting in a kernel crash. This patch fixes this race by protecting the sysfs file creation/notification by holding a reference count on kobject until we safely send kobject_uevent(). The function create_dump_obj() returns the dump object which if used by caller function will end up in use-after-free problem again. However, the return value of create_dump_obj() function isn't being used today and there is no need as well. Hence change it to return void to make this fix complete. Fixes: c7e64b9ce04a ("powerpc/powernv Platform dump interface") Signed-off-by: Vasant Hegde Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201017164210.264619-1-hegdevasant@linux.vnet.ibm.com Signed-off-by: Sasha Levin

powerpc/book3s: Fix MCE console messages for unrecoverable MCE.

2020-05-10T08:26:08+00:00

commit c74dd88e77d3ecbc9e55c78796d82c9aa21cabad upstream. When machine check occurs with MSR(RI=0), it means MC interrupt is unrecoverable and kernel goes down to panic path. But the console message still shows it as recovered. This patch fixes the MCE console messages. Fixes: 36df96f8acaf ("powerpc/book3s: Decode and save machine check event.") Signed-off-by: Mahesh Salgaonkar Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman

powerpc/powernv: Restrict OPAL symbol map to only be readable by root

2019-10-17T20:40:53+00:00

commit e7de4f7b64c23e503a8c42af98d56f2a7462bd6d upstream. Currently the OPAL symbol map is globally readable, which seems bad as it contains physical addresses. Restrict it to root. Fixes: c8742f85125d ("powerpc/powernv: Expose OPAL firmware symbol map") Cc: stable@vger.kernel.org # v3.19+ Suggested-by: Michael Ellerman Signed-off-by: Andrew Donnellan Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190503075253.22798-1-ajd@linux.ibm.com Signed-off-by: Greg Kroah-Hartman

powerpc/powernv: Query firmware for count cache flush settings

2019-05-16T17:44:50+00:00

commit 99d54754d3d5f896a8f616b0b6520662bc99d66b upstream. Look for fw-features properties to determine the appropriate settings for the count cache flush, and then call the generic powerpc code to set it up based on the security feature flags. Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman