4.4-stable review patch. If anyone has any objections, please let me know.
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From: Bin Yang bin.yang@intel.com
commit 831b624df1b420c8f9281ed1307a8db23afb72df upstream.
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: 24c3d2f342ed ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/pstore/ram_core.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-)
--- a/fs/pstore/ram_core.c +++ b/fs/pstore/ram_core.c @@ -378,7 +378,12 @@ static void *persistent_ram_vmap(phys_ad vaddr = vmap(pages, page_count, VM_MAP, prot); kfree(pages);
- return vaddr; + /* + * Since vmap() uses page granularity, we must add the offset + * into the page here, to get the byte granularity address + * into the mapping to represent the actual "start" location. + */ + return vaddr + offset_in_page(start); }
static void *persistent_ram_iomap(phys_addr_t start, size_t size, @@ -397,6 +402,11 @@ static void *persistent_ram_iomap(phys_a else va = ioremap_wc(start, size);
+ /* + * Since request_mem_region() and ioremap() are byte-granularity + * there is no need handle anything special like we do when the + * vmap() case in persistent_ram_vmap() above. + */ return va; }
@@ -417,7 +427,7 @@ static int persistent_ram_buffer_map(phy return -ENOMEM; }
- prz->buffer = prz->vaddr + offset_in_page(start); + prz->buffer = prz->vaddr; prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
return 0; @@ -464,7 +474,8 @@ void persistent_ram_free(struct persiste
if (prz->vaddr) { if (pfn_valid(prz->paddr >> PAGE_SHIFT)) { - vunmap(prz->vaddr); + /* We must vunmap() at page-granularity. */ + vunmap(prz->vaddr - offset_in_page(prz->paddr)); } else { iounmap(prz->vaddr); release_mem_region(prz->paddr, prz->size);