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| author | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2020-09-22 14:58:46 +0300 |
|---|---|---|
| committer | Vinod Koul <vkoul@kernel.org> | 2020-09-22 20:18:41 +0530 |
| commit | b28de385b71abf31ce68ec0387638bee26ae9024 (patch) | |
| tree | fd4ab881799bdeff66228409eba13e5968e5f1e3 /drivers/dma/dmatest.c | |
| parent | d2dc9ab7476412e30a9ebffdd9fd01a6dc551870 (diff) | |
| download | linux-b28de385b71abf31ce68ec0387638bee26ae9024.tar.gz linux-b28de385b71abf31ce68ec0387638bee26ae9024.tar.bz2 linux-b28de385b71abf31ce68ec0387638bee26ae9024.zip | |
dmaengine: dmatest: Check list for emptiness before access its last entry
After writing a garbage to the channel we get an Oops in dmatest_chan_set()
due to access to last entry in the empty list.
[ 212.670672] BUG: unable to handle page fault for address: fffffff000000020
[ 212.677562] #PF: supervisor read access in kernel mode
[ 212.682702] #PF: error_code(0x0000) - not-present page
...
[ 212.710074] RIP: 0010:dmatest_chan_set+0x149/0x2d0 [dmatest]
[ 212.715739] Code: e8 cc f9 ff ff 48 8b 1d 0d 55 00 00 48 83 7b 10 00 0f 84 63 01 00 00 48 c7 c7 d0 65 4d c0 e8 ee 4a f5 e1 48 89 c6 48 8b 43 10 <48> 8b 40 20 48 8b 78 58 48 85 ff 0f 84 f5 00 00 00 e8 b1 41 f5 e1
Fix this by checking list for emptiness before accessing its last entry.
Fixes: d53513d5dc28 ("dmaengine: dmatest: Add support for multi channel testing")
Cc: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20200922115847.30100-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers/dma/dmatest.c')
| -rw-r--r-- | drivers/dma/dmatest.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c index 5dc3db216602..00f288bd377c 100644 --- a/drivers/dma/dmatest.c +++ b/drivers/dma/dmatest.c @@ -1255,15 +1255,14 @@ static int dmatest_chan_set(const char *val, const struct kernel_param *kp) add_threaded_test(info); /* Check if channel was added successfully */ - dtc = list_last_entry(&info->channels, struct dmatest_chan, node); - - if (dtc->chan) { + if (!list_empty(&info->channels)) { /* * if new channel was not successfully added, revert the * "test_channel" string to the name of the last successfully * added channel. exception for when users issues empty string * to channel parameter. */ + dtc = list_last_entry(&info->channels, struct dmatest_chan, node); if ((strcmp(dma_chan_name(dtc->chan), strim(test_channel)) != 0) && (strcmp("", strim(test_channel)) != 0)) { ret = -EINVAL; |