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-Wsometimes-uninitialized in arch/powerpc/xmon/ppc-dis.c #390

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nickdesaulniers opened this issue Feb 26, 2019 · 4 comments
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-Wsometimes-uninitialized in arch/powerpc/xmon/ppc-dis.c #390

nickdesaulniers opened this issue Feb 26, 2019 · 4 comments
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@nathanchance
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-Wsometimes-uninitialized [ARCH] powerpc This bug impacts ARCH=powerpc [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 5.1 This bug was fixed in Linux 5.1

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@nickdesaulniers
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from #381

arch/powerpc/xmon/ppc-dis.c:157:7: error: variable 'opcode' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
@nickdesaulniers nickdesaulniers added good first issue Good for newcomers [BUG] linux A bug that should be fixed in the mainline kernel. low priority This bug is not critical and not a priority [ARCH] powerpc This bug impacts ARCH=powerpc labels Feb 26, 2019
@nathanchance nathanchance self-assigned this Feb 26, 2019
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I'm drafting the commit message for this one now, it's a good one.

@nathanchance
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Ah C... https://lore.kernel.org/lkml/20190226053855.7020-1-natechancellor@gmail.com/

@nathanchance nathanchance added [PATCH] Submitted A patch has been submitted for review and removed good first issue Good for newcomers low priority This bug is not critical and not a priority labels Feb 26, 2019
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Patch accepted: https://git.kernel.org/powerpc/c/e7140639b1de65bba435a6bd772d1349

@nathanchance nathanchance added [PATCH] Accepted A submitted patch has been accepted upstream and removed [PATCH] Submitted A patch has been submitted for review labels Feb 28, 2019
fengguang pushed a commit to 0day-ci/linux that referenced this issue Mar 6, 2019
@nathanchance @intel-lab-lkp
powerpc/xmon: Fix opcode being uninitialized in print_insn_powerpc
f75b2a2 
When building with -Wsometimes-uninitialized, Clang warns:

arch/powerpc/xmon/ppc-dis.c:157:7: warning: variable 'opcode' is used
uninitialized whenever 'if' condition is false
[-Wsometimes-uninitialized]
  if (cpu_has_feature(CPU_FTRS_POWER9))
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/powerpc/xmon/ppc-dis.c:167:7: note: uninitialized use occurs here
  if (opcode == NULL)
      ^~~~~~
arch/powerpc/xmon/ppc-dis.c:157:3: note: remove the 'if' if its
condition is always true
  if (cpu_has_feature(CPU_FTRS_POWER9))
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/powerpc/xmon/ppc-dis.c:132:38: note: initialize the variable
'opcode' to silence this warning
  const struct powerpc_opcode *opcode;
                                     ^
                                      = NULL
1 warning generated.

This warning seems to make no sense on the surface because opcode is set
to NULL right below this statement. However, there is a comma instead of
semicolon to end the dialect assignment, meaning that the opcode
assignment only happens in the if statement. Properly terminate that
line so that Clang no longer warns.

Fixes: 5b10278 ("powerpc/xmon: Enable disassembly files (compilation changes)")
Link: ClangBuiltLinux#390
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
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Merged into mainline: https://git.kernel.org/torvalds/c/e7140639b1de65bba435a6bd772d1349

@nathanchance nathanchance added [FIXED][LINUX] 5.1 This bug was fixed in Linux 5.1 and removed [PATCH] Accepted A submitted patch has been accepted upstream labels Mar 7, 2019
nathanchance pushed a commit that referenced this issue Mar 11, 2019
@adlazar @davem330
vsock/virtio: fix kernel panic from virtio_transport_reset_no_sock
4c404ce 
Previous to commit 22b5c0b ("vsock/virtio: fix kernel panic
after device hot-unplug"), vsock_core_init() was called from
virtio_vsock_probe(). Now, virtio_transport_reset_no_sock() can be called
before vsock_core_init() has the chance to run.

[Wed Feb 27 14:17:09 2019] BUG: unable to handle kernel NULL pointer dereference at 0000000000000110
[Wed Feb 27 14:17:09 2019] #PF error: [normal kernel read fault]
[Wed Feb 27 14:17:09 2019] PGD 0 P4D 0
[Wed Feb 27 14:17:09 2019] Oops: 0000 [#1] SMP PTI
[Wed Feb 27 14:17:09 2019] CPU: 3 PID: 59 Comm: kworker/3:1 Not tainted 5.0.0-rc7-390-generic-hvi #390
[Wed Feb 27 14:17:09 2019] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[Wed Feb 27 14:17:09 2019] Workqueue: virtio_vsock virtio_transport_rx_work [vmw_vsock_virtio_transport]
[Wed Feb 27 14:17:09 2019] RIP: 0010:virtio_transport_reset_no_sock+0x8c/0xc0 [vmw_vsock_virtio_transport_common]
[Wed Feb 27 14:17:09 2019] Code: 35 8b 4f 14 48 8b 57 08 31 f6 44 8b 4f 10 44 8b 07 48 8d 7d c8 e8 84 f8 ff ff 48 85 c0 48 89 c3 74 2a e8 f7 31 03 00 48 89 df <48> 8b 80 10 01 00 00 e8 68 fb 69 ed 48 8b 75 f0 65 48 33 34 25 28
[Wed Feb 27 14:17:09 2019] RSP: 0018:ffffb42701ab7d40 EFLAGS: 00010282
[Wed Feb 27 14:17:09 2019] RAX: 0000000000000000 RBX: ffff9d79637ee080 RCX: 0000000000000003
[Wed Feb 27 14:17:09 2019] RDX: 0000000000000001 RSI: 0000000000000002 RDI: ffff9d79637ee080
[Wed Feb 27 14:17:09 2019] RBP: ffffb42701ab7d78 R08: ffff9d796fae70e0 R09: ffff9d796f403500
[Wed Feb 27 14:17:09 2019] R10: ffffb42701ab7d90 R11: 0000000000000000 R12: ffff9d7969d09240
[Wed Feb 27 14:17:09 2019] R13: ffff9d79624e6840 R14: ffff9d7969d09318 R15: ffff9d796d48ff80
[Wed Feb 27 14:17:09 2019] FS:  0000000000000000(0000) GS:ffff9d796fac0000(0000) knlGS:0000000000000000
[Wed Feb 27 14:17:09 2019] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[Wed Feb 27 14:17:09 2019] CR2: 0000000000000110 CR3: 0000000427f22000 CR4: 00000000000006e0
[Wed Feb 27 14:17:09 2019] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[Wed Feb 27 14:17:09 2019] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[Wed Feb 27 14:17:09 2019] Call Trace:
[Wed Feb 27 14:17:09 2019]  virtio_transport_recv_pkt+0x63/0x820 [vmw_vsock_virtio_transport_common]
[Wed Feb 27 14:17:09 2019]  ? kfree+0x17e/0x190
[Wed Feb 27 14:17:09 2019]  ? detach_buf_split+0x145/0x160
[Wed Feb 27 14:17:09 2019]  ? __switch_to_asm+0x40/0x70
[Wed Feb 27 14:17:09 2019]  virtio_transport_rx_work+0xa0/0x106 [vmw_vsock_virtio_transport]
[Wed Feb 27 14:17:09 2019] NET: Registered protocol family 40
[Wed Feb 27 14:17:09 2019]  process_one_work+0x167/0x410
[Wed Feb 27 14:17:09 2019]  worker_thread+0x4d/0x460
[Wed Feb 27 14:17:09 2019]  kthread+0x105/0x140
[Wed Feb 27 14:17:09 2019]  ? rescuer_thread+0x360/0x360
[Wed Feb 27 14:17:09 2019]  ? kthread_destroy_worker+0x50/0x50
[Wed Feb 27 14:17:09 2019]  ret_from_fork+0x35/0x40
[Wed Feb 27 14:17:09 2019] Modules linked in: vmw_vsock_virtio_transport vmw_vsock_virtio_transport_common input_leds vsock serio_raw i2c_piix4 mac_hid qemu_fw_cfg autofs4 cirrus ttm drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops virtio_net psmouse drm net_failover pata_acpi virtio_blk failover floppy

Fixes: 22b5c0b ("vsock/virtio: fix kernel panic after device hot-unplug")
Reported-by: Alexandru Herghelegiu <aherghelegiu@bitdefender.com>
Signed-off-by: Adalbert Lazăr <alazar@bitdefender.com>
Co-developed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
@nathanchance nathanchance mentioned this issue Dec 19, 2023
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-Wsometimes-uninitialized [ARCH] powerpc This bug impacts ARCH=powerpc [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 5.1 This bug was fixed in Linux 5.1
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