From: Russell King Date: Mon, 1 Sep 2014 17:07:38 +0000 (+0100) Subject: imx-drm: imx-ldb: fix NULL pointer in imx_ldb_unbind() X-Git-Tag: fixes-for-v3.18-merge-window~135^2~1 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d9fdb9fba7ec08769594abede8f78523ed3f025a;p=pandora-kernel.git imx-drm: imx-ldb: fix NULL pointer in imx_ldb_unbind() When trying to unbind imx-drm, the following oops was observed from the imx-ldb driver: Unable to handle kernel NULL pointer dereference at virtual address 0000001c pgd = de954000 [0000001c] *pgd=2e92c831, *pte=00000000, *ppte=00000000 Internal error: Oops: 17 [#1] SMP ARM Modules linked in: bnep rfcomm bluetooth nfsd exportfs hid_cypress brcmfmac brcmutil snd_soc_fsl_ssi snd_soc_fsl_spdif imx_pcm_fiq imx_pcm_dma imx_ldb(C) imx_thermal imx_sdma imx2_wdt snd_soc_sgtl5000 snd_soc_imx_sgtl5000 snd_soc_imx_spdif snd_soc_imx_audmux CPU: 1 PID: 1228 Comm: bash Tainted: G C 3.16.0-rc2+ #1229 task: ea378d80 ti: de948000 task.ti: de948000 PC is at imx_ldb_unbind+0x1c/0x58 [imx_ldb] LR is at component_unbind+0x38/0x70 pc : [] lr : [] psr: 200f0013 sp : de949da8 ip : de949dc0 fp : de949dbc r10: e9a44b0c r9 : 00000000 r8 : de949f78 r7 : 00000012 r6 : e9b3f400 r5 : e9b133b8 r4 : e9b13010 r3 : 00000000 r2 : e9b3f400 r1 : ea9a0210 r0 : e9b13020 Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user Control: 10c53c7d Table: 2e95404a DAC: 00000015 Process bash (pid: 1228, stack limit = 0xde948240) Stack: (0xde949da8 to 0xde94a000) ... Backtrace: [] (imx_ldb_unbind [imx_ldb]) from [] (component_unbind+0x38/0x70) [] (component_unbind) from [] (component_unbind_all+0x94/0xc8) [] (component_unbind_all) from [] (imx_drm_driver_unload+0x34/0x4c) [] (imx_drm_driver_unload) from [] (drm_dev_unregister+0x2c/0xa0) [] (drm_dev_unregister) from [] (drm_put_dev+0x30/0x6c) [] (drm_put_dev) from [] (imx_drm_unbind+0x14/0x18) [] (imx_drm_unbind) from [] (component_master_del+0xbc/0xd8) ... Code: e5904058 e2840010 e2845fea e59430a0 (e593301c) ---[ end trace 4f211c6dbbcd4963 ]--- This is caused by only having one channel out of the pair configured in DT; the second channel remains uninitialised, but upon unbind, the driver attempts to clean up both, thereby dereferencing a NULL pointer. Avoid this by checking that the second channel is initialised. Fixes: 1b3f76756633 ("imx-drm: initialise drm components directly") Cc: Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman --- Reading git-diff-tree failed