Message-ID: <20160829060505.GF10980@phenom.ffwll.local>
Date:   Mon, 29 Aug 2016 08:05:05 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     airlied@...ux.ie, dri-devel@...ts.freedesktop.org,
        LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Kostya Serebryany <kcc@...gle.com>,
        syzkaller <syzkaller@...glegroups.com>,
        Alexander Potapenko <glider@...gle.com>
Subject: Re: drm: WARNING in ioremap_wc

On Sun, Aug 28, 2016 at 07:36:59PM +0200, Dmitry Vyukov wrote:
> Hello,
> 
> The following program triggers WARNING in ioremap_wc:

Yup, that should also be fixed in linux-next. Probably better to not
report more for 4.8-rc kernels for now ;-)

If you have some time to test, you need to cherry pick the following two
patches I think:

fa5386459f06 ("drm: Used DRM_LEGACY for all legacy functions")
3cbf6a5deb2f ("drm: Mark up legacy/dri1 drivers with DRM_LEGACY")

If that's confirmed we can cherry-pick them over to -fixes.
-Daniel

> 
> ------------[ cut here ]------------
> LoadPin: kernel-module denied obj="/memfd: (deleted)" pid=12061
> cmdline="/tmp/syz-executor"
> WARNING: CPU: 1 PID: 12056 at arch/x86/mm/ioremap.c:121[<      none
>   >] __ioremap_caller+0x348/0x6b0 arch/x86/mm/ioremap.c:120
> LoadPin: kernel-module denied obj="/memfd: (deleted)" pid=12063
> cmdline="/tmp/syz-executor"
> ioremap on RAM at 0x0000000020068000 - 0x0000000020068fff
> Kernel panic - not syncing: panic_on_warn set ...
> 
> CPU: 1 PID: 12056 Comm: syz-executor Not tainted 4.8.0-rc3+ #32
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>  ffffffff884b8280 ffff8800295777f0 ffffffff82d1b239 ffffffff00bd6000
>  fffffbfff1097050 ffffffff86e8eec0 ffff8800295778c8 ffffffff86e7ad00
>  dffffc0000000000 0000000000000009 ffff8800295778b8 ffffffff816ab4e3
> Call Trace:
>  [<     inline     >] __dump_stack lib/dump_stack.c:15
>  [<ffffffff82d1b239>] dump_stack+0x12e/0x185 lib/dump_stack.c:51
>  [<ffffffff816ab4e3>] panic+0x1e4/0x3ef kernel/panic.c:153
>  [<ffffffff813808f4>] __warn+0x1c4/0x1e0 kernel/panic.c:509
>  [<ffffffff813809bc>] warn_slowpath_fmt+0xac/0xd0 kernel/panic.c:532
>  [<ffffffff8129a1c8>] __ioremap_caller+0x348/0x6b0 arch/x86/mm/ioremap.c:120
>  [<ffffffff8129a5b6>] ioremap_wc+0x26/0x30 arch/x86/mm/ioremap.c:290
>  [<ffffffff833ff70e>] drm_addmap_core+0xf1e/0x16c0
> drivers/gpu/drm/drm_bufs.c:213
>  [<ffffffff8340327a>] drm_legacy_addmap_ioctl+0x1ca/0x340
> drivers/gpu/drm/drm_bufs.c:403
>  [<ffffffff83410a5c>] drm_ioctl+0x7bc/0xc60 drivers/gpu/drm/drm_ioctl.c:724
>  [<     inline     >] vfs_ioctl fs/ioctl.c:43
>  [<ffffffff8186f1fc>] do_vfs_ioctl+0x18c/0x1080 fs/ioctl.c:675
>  [<     inline     >] SYSC_ioctl fs/ioctl.c:690
>  [<ffffffff8187017f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:681
>  [<ffffffff810088ff>] do_syscall_64+0x1df/0x640 arch/x86/entry/common.c:288
>  [<ffffffff86c25543>] entry_SYSCALL64_slow_path+0x25/0x25
> arch/x86/entry/entry_64.S:248
> 
> On commit 61c04572de404e52a655a36752e696bbcb483cf5 (Aug 25).
> 
> 
> // autogenerated by syzkaller (http://github.com/google/syzkaller)
> #ifndef __NR_syz_open_pts
> #define __NR_syz_open_pts 1000002
> #endif
> #ifndef __NR_mmap
> #define __NR_mmap 9
> #endif
> #ifndef __NR_syz_open_dev
> #define __NR_syz_open_dev 1000001
> #endif
> #ifndef __NR_ioctl
> #define __NR_ioctl 16
> #endif
> #ifndef __NR_syz_fuse_mount
> #define __NR_syz_fuse_mount 1000003
> #endif
> #ifndef __NR_syz_fuseblk_mount
> #define __NR_syz_fuseblk_mount 1000004
> #endif
> 
> #include <fcntl.h>
> #include <pthread.h>
> #include <setjmp.h>
> #include <signal.h>
> #include <stddef.h>
> #include <stdint.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> #include <sys/ioctl.h>
> #include <sys/stat.h>
> #include <sys/syscall.h>
> #include <sys/types.h>
> #include <unistd.h>
> 
> __thread int skip_segv;
> __thread jmp_buf segv_env;
> 
> static void segv_handler(int sig, siginfo_t* info, void* uctx)
> {
>   if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED))
>     _longjmp(segv_env, 1);
>   exit(sig);
> }
> 
> static void install_segv_handler()
> {
>   struct sigaction sa;
>   memset(&sa, 0, sizeof(sa));
>   sa.sa_sigaction = segv_handler;
>   sa.sa_flags = SA_NODEFER | SA_SIGINFO;
>   sigaction(SIGSEGV, &sa, NULL);
>   sigaction(SIGBUS, &sa, NULL);
> }
> 
> #define NONFAILING(...)                                                \
>   {                                                                    \
>     __atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST);               \
>     if (_setjmp(segv_env) == 0) {                                      \
>       __VA_ARGS__;                                                     \
>     }                                                                  \
>     __atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST);               \
>   }
> 
> static uintptr_t syz_open_dev(uintptr_t a0, uintptr_t a1, uintptr_t a2)
> {
>   if (a0 == 0xc || a0 == 0xb) {
>     char buf[128];
>     sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block",
>             (uint8_t)a1, (uint8_t)a2);
>     return open(buf, O_RDWR, 0);
>   } else {
>     char buf[1024];
>     char* hash;
>     strncpy(buf, (char*)a0, sizeof(buf));
>     buf[sizeof(buf) - 1] = 0;
>     while ((hash = strchr(buf, '#'))) {
>       *hash = '0' + (char)(a1 % 10);
>       a1 /= 10;
>     }
>     return open(buf, a2, 0);
>   }
> }
> 
> static uintptr_t syz_open_pts(uintptr_t a0, uintptr_t a1)
> {
>   int ptyno = 0;
>   if (ioctl(a0, TIOCGPTN, &ptyno))
>     return -1;
>   char buf[128];
>   sprintf(buf, "/dev/pts/%d", ptyno);
>   return open(buf, a1, 0);
> }
> 
> static uintptr_t syz_fuse_mount(uintptr_t a0, uintptr_t a1,
>                                 uintptr_t a2, uintptr_t a3,
>                                 uintptr_t a4, uintptr_t a5)
> {
>   uint64_t target = a0;
>   uint64_t mode = a1;
>   uint64_t uid = a2;
>   uint64_t gid = a3;
>   uint64_t maxread = a4;
>   uint64_t flags = a5;
> 
>   int fd = open("/dev/fuse", O_RDWR);
>   if (fd == -1)
>     return fd;
>   char buf[1024];
>   sprintf(buf, "fd=%d,user_id=%ld,group_id=%ld,rootmode=0%o", fd,
>           (long)uid, (long)gid, (unsigned)mode & ~3u);
>   if (maxread != 0)
>     sprintf(buf + strlen(buf), ",max_read=%ld", (long)maxread);
>   if (mode & 1)
>     strcat(buf, ",default_permissions");
>   if (mode & 2)
>     strcat(buf, ",allow_other");
>   syscall(SYS_mount, "", target, "fuse", flags, buf);
>   return fd;
> }
> 
> static uintptr_t syz_fuseblk_mount(uintptr_t a0, uintptr_t a1,
>                                    uintptr_t a2, uintptr_t a3,
>                                    uintptr_t a4, uintptr_t a5,
>                                    uintptr_t a6, uintptr_t a7)
> {
>   uint64_t target = a0;
>   uint64_t blkdev = a1;
>   uint64_t mode = a2;
>   uint64_t uid = a3;
>   uint64_t gid = a4;
>   uint64_t maxread = a5;
>   uint64_t blksize = a6;
>   uint64_t flags = a7;
> 
>   int fd = open("/dev/fuse", O_RDWR);
>   if (fd == -1)
>     return fd;
>   if (syscall(SYS_mknodat, AT_FDCWD, blkdev, S_IFBLK, makedev(7, 199)))
>     return fd;
>   char buf[256];
>   sprintf(buf, "fd=%d,user_id=%ld,group_id=%ld,rootmode=0%o", fd,
>           (long)uid, (long)gid, (unsigned)mode & ~3u);
>   if (maxread != 0)
>     sprintf(buf + strlen(buf), ",max_read=%ld", (long)maxread);
>   if (blksize != 0)
>     sprintf(buf + strlen(buf), ",blksize=%ld", (long)blksize);
>   if (mode & 1)
>     strcat(buf, ",default_permissions");
>   if (mode & 2)
>     strcat(buf, ",allow_other");
>   syscall(SYS_mount, blkdev, target, "fuseblk", flags, buf);
>   return fd;
> }
> 
> static uintptr_t execute_syscall(int nr, uintptr_t a0, uintptr_t a1,
>                                  uintptr_t a2, uintptr_t a3,
>                                  uintptr_t a4, uintptr_t a5,
>                                  uintptr_t a6, uintptr_t a7,
>                                  uintptr_t a8)
> {
>   switch (nr) {
>   default:
>     return syscall(nr, a0, a1, a2, a3, a4, a5);
>   case __NR_syz_open_dev:
>     return syz_open_dev(a0, a1, a2);
>   case __NR_syz_open_pts:
>     return syz_open_pts(a0, a1);
>   case __NR_syz_fuse_mount:
>     return syz_fuse_mount(a0, a1, a2, a3, a4, a5);
>   case __NR_syz_fuseblk_mount:
>     return syz_fuseblk_mount(a0, a1, a2, a3, a4, a5, a6, a7);
>   }
> }
> 
> long r[10];
> 
> int main()
> {
>   install_segv_handler();
>   memset(r, -1, sizeof(r));
>   r[0] = execute_syscall(__NR_mmap, 0x20000000ul, 0x85a000ul, 0x3ul,
>                          0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0);
>   NONFAILING(memcpy(
>       (void*)0x20000000,
>       "\x2f\x64\x65\x76\x2f\x64\x72\x69\x2f\x63\x61\x72\x64\x23\x00",
>       15));
>   r[2] = execute_syscall(__NR_syz_open_dev, 0x20000000ul, 0x0ul,
>                          0x400ul, 0, 0, 0, 0, 0, 0);
>   NONFAILING(*(uint64_t*)0x20858fd8 = (uint64_t)0x20068000);
>   NONFAILING(*(uint64_t*)0x20858fe0 = (uint64_t)0x1000);
>   NONFAILING(*(uint32_t*)0x20858fe8 = (uint32_t)0x1);
>   NONFAILING(*(uint32_t*)0x20858fec = (uint32_t)0x30);
>   NONFAILING(*(uint64_t*)0x20858ff0 = (uint64_t)0x20284000);
>   NONFAILING(*(uint32_t*)0x20858ff8 = (uint32_t)0x1);
>   r[9] = execute_syscall(__NR_ioctl, r[2], 0xc0286415ul, 0x20858fd8ul,
>                          0, 0, 0, 0, 0, 0);
>   return 0;
> }
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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