linux/fs/pstore
Bin Yang 831b624df1 pstore: Fix incorrect persistent ram buffer mapping
persistent_ram_vmap() returns the page start vaddr.
persistent_ram_iomap() supports non-page-aligned mapping.

persistent_ram_buffer_map() always adds offset-in-page to the vaddr
returned from these two functions, which causes incorrect mapping of
non-page-aligned persistent ram buffer.

By default ftrace_size is 4096 and max_ftrace_cnt is nr_cpu_ids. Without
this patch, the zone_sz in ramoops_init_przs() is 4096/nr_cpu_ids which
might not be page aligned. If the offset-in-page > 2048, the vaddr will be
in next page. If the next page is not mapped, it will cause kernel panic:

[    0.074231] BUG: unable to handle kernel paging request at ffffa19e0081b000
...
[    0.075000] RIP: 0010:persistent_ram_new+0x1f8/0x39f
...
[    0.075000] Call Trace:
[    0.075000]  ramoops_init_przs.part.10.constprop.15+0x105/0x260
[    0.075000]  ramoops_probe+0x232/0x3a0
[    0.075000]  platform_drv_probe+0x3e/0xa0
[    0.075000]  driver_probe_device+0x2cd/0x400
[    0.075000]  __driver_attach+0xe4/0x110
[    0.075000]  ? driver_probe_device+0x400/0x400
[    0.075000]  bus_for_each_dev+0x70/0xa0
[    0.075000]  driver_attach+0x1e/0x20
[    0.075000]  bus_add_driver+0x159/0x230
[    0.075000]  ? do_early_param+0x95/0x95
[    0.075000]  driver_register+0x70/0xc0
[    0.075000]  ? init_pstore_fs+0x4d/0x4d
[    0.075000]  __platform_driver_register+0x36/0x40
[    0.075000]  ramoops_init+0x12f/0x131
[    0.075000]  do_one_initcall+0x4d/0x12c
[    0.075000]  ? do_early_param+0x95/0x95
[    0.075000]  kernel_init_freeable+0x19b/0x222
[    0.075000]  ? rest_init+0xbb/0xbb
[    0.075000]  kernel_init+0xe/0xfc
[    0.075000]  ret_from_fork+0x3a/0x50

Signed-off-by: Bin Yang <bin.yang@intel.com>
[kees: add comments describing the mapping differences, updated commit log]
Fixes: 24c3d2f342 ("staging: android: persistent_ram: Make it possible to use memory outside of bootmem")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
2018-09-13 09:14:57 -07:00
..
Kconfig pstore: add zstd compression support 2018-08-03 18:12:18 -07:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ftrace.c pstore: Remove write_buf() callback 2017-03-07 14:01:02 -08:00
inode.c vfs: change inode times to use struct timespec64 2018-06-05 16:57:31 -07:00
internal.h pstore: Select compression at runtime 2018-03-07 12:43:35 -08:00
platform.c pstore: add zstd compression support 2018-08-03 18:12:18 -07:00
pmsg.c pstore: Create common record initializer 2017-05-31 10:13:44 -07:00
ram.c pstore: Remove bogus format string definition 2018-06-14 14:57:24 +02:00
ram_core.c pstore: Fix incorrect persistent ram buffer mapping 2018-09-13 09:14:57 -07:00