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Pr fix drm pgattr #61

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andr2000
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YueHaibing and others added 2 commits February 21, 2019 14:50
[ Upstream commit 938010a ]

There is no need to have the 'struct drm_framebuffer *fb' variable
static since new value always be assigned before use it.

Signed-off-by: YueHaibing <[email protected]>
Reviewed-by: Oleksandr Andrushchenko <[email protected]>
Signed-off-by: Oleksandr Andrushchenko <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
[ Upstream commit 24ded29 ]

When GEM backing storage is allocated those are normal pages,
so there is no point using pgprot_writecombine while mmaping.
This fixes mismatch of buffer pages' memory attributes between
the frontend and backend which may cause screen artifacts.

Fixes: c575b7e ("drm/xen-front: Add support for Xen PV display frontend")

Signed-off-by: Oleksandr Andrushchenko <[email protected]>
Suggested-by: Julien Grall <[email protected]>
Acked-by: Julien Grall <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
@andr2000
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@iartemenko pls merge

@andr2000
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@iartemenko pls merge

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@iartemenko bump

@iartemenko iartemenko merged commit ba372bf into xen-troops:android-4.14-p-release-xt0.2 Feb 26, 2019
arminn pushed a commit to arminn/linux that referenced this pull request Aug 9, 2021
commit 704adfb upstream.

The histogram logic was allowing events with char * pointers to be used as
normal strings. But it was easy to crash the kernel with:

 # echo 'hist:keys=filename' > events/syscalls/sys_enter_openat/trigger

And open some files, and boom!

 BUG: unable to handle page fault for address: 00007f2ced0c3280
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 1173fa067 P4D 1173fa067 PUD 1171b6067 PMD 1171dd067 PTE 0
 Oops: 0000 [xen-troops#1] PREEMPT SMP
 CPU: 6 PID: 1810 Comm: cat Not tainted 5.13.0-rc5-test+ xen-troops#61
 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01
v03.03 07/14/2016
 RIP: 0010:strlen+0x0/0x20
 Code: f6 82 80 2a 0b a9 20 74 11 0f b6 50 01 48 83 c0 01 f6 82 80 2a 0b
a9 20 75 ef c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 <80> 3f 00 74
10 48 89 f8 48 83 c0 01 80 38 00 75 f7 48 29 f8 c3

 RSP: 0018:ffffbdbf81567b50 EFLAGS: 00010246
 RAX: 0000000000000003 RBX: ffff93815cdb3800 RCX: ffff9382401a22d0
 RDX: 0000000000000100 RSI: 0000000000000000 RDI: 00007f2ced0c3280
 RBP: 0000000000000100 R08: ffff9382409ff074 R09: ffffbdbf81567c98
 R10: ffff9382409ff074 R11: 0000000000000000 R12: ffff9382409ff074
 R13: 0000000000000001 R14: ffff93815a744f00 R15: 00007f2ced0c3280
 FS:  00007f2ced0f8580(0000) GS:ffff93825a800000(0000)
knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007f2ced0c3280 CR3: 0000000107069005 CR4: 00000000001706e0
 Call Trace:
  event_hist_trigger+0x463/0x5f0
  ? find_held_lock+0x32/0x90
  ? sched_clock_cpu+0xe/0xd0
  ? lock_release+0x155/0x440
  ? kernel_init_free_pages+0x6d/0x90
  ? preempt_count_sub+0x9b/0xd0
  ? kernel_init_free_pages+0x6d/0x90
  ? get_page_from_freelist+0x12c4/0x1680
  ? __rb_reserve_next+0xe5/0x460
  ? ring_buffer_lock_reserve+0x12a/0x3f0
  event_triggers_call+0x52/0xe0
  ftrace_syscall_enter+0x264/0x2c0
  syscall_trace_enter.constprop.0+0x1ee/0x210
  do_syscall_64+0x1c/0x80
  entry_SYSCALL_64_after_hwframe+0x44/0xae

Where it triggered a fault on strlen(key) where key was the filename.

The reason is that filename is a char * to user space, and the histogram
code just blindly dereferenced it, with obvious bad results.

I originally tried to use strncpy_from_user/kernel_nofault() but found
that there's other places that its dereferenced and not worth the effort.

Just do not allow "char *" to act like strings.

Link: https://lkml.kernel.org/r/[email protected]

Cc: Ingo Molnar <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Tzvetomir Stoyanov <[email protected]>
Cc: [email protected]
Acked-by: Namhyung Kim <[email protected]>
Acked-by: Tom Zanussi <[email protected]>
Fixes: 79e577c ("tracing: Support string type key properly")
Fixes: 5967bd5 ("tracing: Let filter_assign_type() detect FILTER_PTR_STRING")
Signed-off-by: Steven Rostedt (VMware) <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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3 participants