[ Upstream commit bd68ffce69f6cf8ddd3a3c32549d1d2275e49fc5 ]
dlpar_memory_remove_by_index() may access beyond the bounds of the
drmem lmb array when the LMB lookup fails to match an entry with the
given DRC index. When the search fails, the cursor is left pointing to
&drmem_info->lmbs[drmem_info->n_lmbs], which is one element past the
last valid entry in the array. The debug message at the end of the
function then dereferences this pointer:
pr_debug("Failed to hot-remove memory at %llx\n",
lmb->base_addr);
This was found by inspection and confirmed with KASAN:
pseries-hotplug-mem: Attempting to hot-remove LMB, drc index 1234
==================================================================
BUG: KASAN: slab-out-of-bounds in dlpar_memory+0x298/0x1658
Read of size 8 at addr c000000364e97fd0 by task bash/949
dump_stack_lvl+0xa4/0xfc (unreliable)
print_report+0x214/0x63c
kasan_report+0x140/0x2e0
__asan_load8+0xa8/0xe0
dlpar_memory+0x298/0x1658
handle_dlpar_errorlog+0x130/0x1d0
dlpar_store+0x18c/0x3e0
kobj_attr_store+0x68/0xa0
sysfs_kf_write+0xc4/0x110
kernfs_fop_write_iter+0x26c/0x390
vfs_write+0x2d4/0x4e0
ksys_write+0xac/0x1a0
system_call_exception+0x268/0x530
system_call_vectored_common+0x15c/0x2ec
Allocated by task 1:
kasan_save_stack+0x48/0x80
kasan_set_track+0x34/0x50
kasan_save_alloc_info+0x34/0x50
__kasan_kmalloc+0xd0/0x120
__kmalloc+0x8c/0x320
kmalloc_array.constprop.0+0x48/0x5c
drmem_init+0x2a0/0x41c
do_one_initcall+0xe0/0x5c0
kernel_init_freeable+0x4ec/0x5a0
kernel_init+0x30/0x1e0
ret_from_kernel_user_thread+0x14/0x1c
The buggy address belongs to the object at c000000364e80000
which belongs to the cache kmalloc-128k of size 131072
The buggy address is located 0 bytes to the right of
allocated 98256-byte region [c000000364e80000, c000000364e97fd0)
==================================================================
pseries-hotplug-mem: Failed to hot-remove memory at 0
Log failed lookups with a separate message and dereference the
cursor only when it points to a valid entry.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Fixes: 51925fb3c5c9 ("powerpc/pseries: Implement memory hotplug remove in the kernel")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231114-pseries-memhp-fixes-v1-1-fb8f2bb7c557@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 20e9de85edae3a5866f29b6cce87c9ec66d62a1b ]
When attempting to remove by index a set of LMBs a lot of messages are
displayed on the console, even when everything goes fine:
pseries-hotplug-mem: Attempting to hot-remove LMB, drc index 8000002d
Offlined Pages 4096
pseries-hotplug-mem: Memory at 2d0000000 was hot-removed
The 2 messages prefixed by "pseries-hotplug-mem" are not really
helpful for the end user, they should be debug outputs.
In case of error, because some of the LMB's pages couldn't be
offlined, the following is displayed on the console:
pseries-hotplug-mem: Attempting to hot-remove LMB, drc index 8000003e
pseries-hotplug-mem: Failed to hot-remove memory at 3e0000000
dlpar: Could not handle DLPAR request "memory remove index 0x8000003e"
Again, the 2 messages prefixed by "pseries-hotplug-mem" are useless,
and the generic DLPAR prefixed message should be enough.
These 2 first changes are mainly triggered by the changes introduced
in drmgr:
https://groups.google.com/g/powerpc-utils-devel/c/Y6ef4NB3EzM/m/9cu5JHRxAQAJ
Also, when adding a bunch of LMBs, a message is displayed in the console per LMB
like these ones:
pseries-hotplug-mem: Memory at 7e0000000 (drc index 8000007e) was hot-added
pseries-hotplug-mem: Memory at 7f0000000 (drc index 8000007f) was hot-added
pseries-hotplug-mem: Memory at 800000000 (drc index 80000080) was hot-added
pseries-hotplug-mem: Memory at 810000000 (drc index 80000081) was hot-added
When adding 1TB of memory and LMB size is 256MB, this leads to 4096
messages to be displayed on the console. These messages are not really
helpful for the end user, so moving them to the DEBUG level.
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
[mpe: Tweak change log wording]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201211145954.90143-1-ldufour@linux.ibm.com
Stable-dep-of: bd68ffce69f6 ("powerpc/pseries/memhp: Fix access beyond end of drmem array")
Signed-off-by: Sasha Levin <sashal@kernel.org>
