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a25a23cc85
When midi function is created, 'id' attribute is initialized with SNDRV_DEFAULT_STR1, which is NULL pointer. Trying to read this attribute before filling it ends up with segmentation fault. This commit fix this issue by preventing null pointer dereference. Now f_midi_opts_id_show() returns empty string when id is a null pointer. Reproduction path: $ mkdir functions/midi.0 $ cat functions/midi.0/id [ 53.130132] Unable to handle kernel NULL pointer dereference at virtual address 00000000 [ 53.132630] pgd = ec6cc000 [ 53.135308] [00000000] *pgd=6b759831, *pte=00000000, *ppte=00000000 [ 53.141530] Internal error: Oops: 17 [#1] PREEMPT SMP ARM [ 53.146904] Modules linked in: usb_f_midi snd_rawmidi libcomposite [ 53.153071] CPU: 1 PID: 2936 Comm: cat Not tainted 3.19.0-00041-gcf4b216 #7 [ 53.160010] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) [ 53.166088] task: ee234c80 ti: ec764000 task.ti: ec764000 [ 53.171482] PC is at strlcpy+0x8/0x60 [ 53.175128] LR is at f_midi_opts_id_show+0x28/0x3c [usb_f_midi] [ 53.181019] pc : [<c0222a9c>] lr : [<bf01bed0>] psr: 60000053 [ 53.181019] sp : ec765ef8 ip : 00000141 fp : 00000000 [ 53.192474] r10: 00019000 r9 : ed7546c0 r8 : 00010000 [ 53.197682] r7 : ec765f80 r6 : eb46a000 r5 : eb46a000 r4 : ed754734 [ 53.204192] r3 : ee234c80 r2 : 00001000 r1 : 00000000 r0 : eb46a000 [ 53.210704] Flags: nZCv IRQs on FIQs off Mode SVC_32 ISA ARM Segment user [ 53.217907] Control: 10c5387d Table: 6c6cc04a DAC: 00000015 [ 53.223636] Process cat (pid: 2936, stack limit = 0xec764238) [ 53.229364] Stack: (0xec765ef8 to 0xec766000) [ 53.233706] 5ee0: ed754734 ed7546c0 [ 53.241866] 5f00: eb46a000 bf01bed0 eb753b80 bf01cc44 eb753b98 bf01b0a4 bf01b08c c0125dd0 [ 53.250025] 5f20: 00002f19 00000000 ec432e00 bf01cce8 c0530c00 00019000 00010000 ec765f80 [ 53.258184] 5f40: 00010000 ec764000 00019000 c00cc4ac ec432e00 c00cc55c 00000017 000081a4 [ 53.266343] 5f60: 00000001 00000000 00000000 ec432e00 ec432e00 00010000 00019000 c00cc620 [ 53.274502] 5f80: 00000000 00000000 00000000 00010000 ffff1000 00019000 00000003 c000e9a8 [ 53.282662] 5fa0: 00000000 c000e7e0 00010000 ffff1000 00000003 00019000 00010000 00019000 [ 53.290821] 5fc0: 00010000 ffff1000 00019000 00000003 7fffe000 00000001 00000000 00000000 [ 53.298980] 5fe0: 00000000 be8c68d4 0000b995 b6f0e3e6 40000070 00000003 00000000 00000000 [ 53.307157] [<c0222a9c>] (strlcpy) from [<bf01bed0>] (f_midi_opts_id_show+0x28/0x3c [usb_f_midi]) [ 53.316006] [<bf01bed0>] (f_midi_opts_id_show [usb_f_midi]) from [<bf01b0a4>] (f_midi_opts_attr_show+0x18/0x24 ) [ 53.327209] [<bf01b0a4>] (f_midi_opts_attr_show [usb_f_midi]) from [<c0125dd0>] (configfs_read_file+0x9c/0xec) [ 53.337180] [<c0125dd0>] (configfs_read_file) from [<c00cc4ac>] (__vfs_read+0x18/0x4c) [ 53.345073] [<c00cc4ac>] (__vfs_read) from [<c00cc55c>] (vfs_read+0x7c/0x100) [ 53.352190] [<c00cc55c>] (vfs_read) from [<c00cc620>] (SyS_read+0x40/0x8c) [ 53.359056] [<c00cc620>] (SyS_read) from [<c000e7e0>] (ret_fast_syscall+0x0/0x34) [ 53.366513] Code: ebffe3d3 e8bd8008 e92d4070 e1a05000 (e5d14000) [ 53.372641] ---[ end trace e4f53a4e233d98d0 ]--- Signed-off-by: Pawel Szewczyk <p.szewczyk@samsung.com> Signed-off-by: Felipe Balbi <balbi@ti.com> |
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| .. | ||
| accessibility | ||
| acpi | ||
| amba | ||
| android | ||
| ata | ||
| atm | ||
| auxdisplay | ||
| base | ||
| bcma | ||
| block | ||
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| bus | ||
| cdrom | ||
| char | ||
| clk | ||
| clocksource | ||
| connector | ||
| cpufreq | ||
| cpuidle | ||
| crypto | ||
| dca | ||
| devfreq | ||
| dio | ||
| dma | ||
| dma-buf | ||
| edac | ||
| eisa | ||
| extcon | ||
| firewire | ||
| firmware | ||
| fmc | ||
| gpio | ||
| gpu | ||
| hid | ||
| hsi | ||
| hv | ||
| hwmon | ||
| hwspinlock | ||
| hwtracing/coresight | ||
| i2c | ||
| ide | ||
| idle | ||
| iio | ||
| infiniband | ||
| input | ||
| iommu | ||
| ipack | ||
| irqchip | ||
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| lguest | ||
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| Makefile | ||