From: Heiko Carstens Date: Tue, 9 Aug 2016 10:26:28 +0000 (+0200) Subject: s390/pageattr: handle numpages parameter correctly X-Git-Tag: v4.8-rc3~25^2~1 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=4d81aaa53c2dea220ddf88e19c33033d6cf4f8cb;p=karo-tx-linux.git s390/pageattr: handle numpages parameter correctly Both set_memory_ro() and set_memory_rw() will modify the page attributes of at least one page, even if the numpages parameter is zero. The author expected that calling these functions with numpages == zero would never happen. However with the new 444d13ff10fb ("modules: add ro_after_init support") feature this happens frequently. Therefore do the right thing and make these two functions return gracefully if nothing should be done. Fixes crashes on module load like this one: Unable to handle kernel pointer dereference in virtual kernel address space Failing address: 000003ff80008000 TEID: 000003ff80008407 Fault in home space mode while using kernel ASCE. AS:0000000000d18007 R3:00000001e6aa4007 S:00000001e6a10800 P:00000001e34ee21d Oops: 0004 ilc:3 [#1] SMP Modules linked in: x_tables CPU: 10 PID: 1 Comm: systemd Not tainted 4.7.0-11895-g3fa9045 #4 Hardware name: IBM 2964 N96 703 (LPAR) task: 00000001e9118000 task.stack: 00000001e9120000 Krnl PSW : 0704e00180000000 00000000005677f8 (rb_erase+0xf0/0x4d0) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3 Krnl GPRS: 000003ff80008b20 000003ff80008b20 000003ff80008b70 0000000000b9d608 000003ff80008b20 0000000000000000 00000001e9123e88 000003ff80008950 00000001e485ab40 000003ff00000000 000003ff80008b00 00000001e4858480 0000000100000000 000003ff80008b68 00000000001d5998 00000001e9123c28 Krnl Code: 00000000005677e8: ec1801c3007c cgij %r1,0,8,567b6e 00000000005677ee: e32010100020 cg %r2,16(%r1) #00000000005677f4: a78401c2 brc 8,567b78 >00000000005677f8: e35010080024 stg %r5,8(%r1) 00000000005677fe: ec5801af007c cgij %r5,0,8,567b5c 0000000000567804: e30050000024 stg %r0,0(%r5) 000000000056780a: ebacf0680004 lmg %r10,%r12,104(%r15) 0000000000567810: 07fe bcr 15,%r14 Call Trace: ([<000003ff80008900>] __this_module+0x0/0xffffffffffffd700 [x_tables]) ([<0000000000264fd4>] do_init_module+0x12c/0x220) ([<00000000001da14a>] load_module+0x24e2/0x2b10) ([<00000000001da976>] SyS_finit_module+0xbe/0xd8) ([<0000000000803b26>] system_call+0xd6/0x264) Last Breaking-Event-Address: [<000000000056771a>] rb_erase+0x12/0x4d0 Kernel panic - not syncing: Fatal exception: panic_on_oops Reported-by: Christian Borntraeger Reported-and-tested-by: Sebastian Ott Fixes: e8a97e42dc98 ("s390/pageattr: allow kernel page table splitting") Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c index 7104ffb5a67f..af7cf28cf97e 100644 --- a/arch/s390/mm/pageattr.c +++ b/arch/s390/mm/pageattr.c @@ -252,6 +252,8 @@ static int change_page_attr(unsigned long addr, unsigned long end, int rc = -EINVAL; pgd_t *pgdp; + if (addr == end) + return 0; if (end >= MODULES_END) return -EINVAL; mutex_lock(&cpa_mutex);