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dmabuf: fix NULL pointer dereference in dma_buf_release()
BugLink: https://bugs.launchpad.net/bugs/1898076 commit 19a508b upstream. NULL pointer dereference is observed while exporting the dmabuf but failed to allocate the 'struct file' which results into the dropping of the allocated dentry corresponding to this file in the dmabuf fs, which is ending up in dma_buf_release() and accessing the uninitialzed dentry->d_fsdata. Call stack on 5.4 is below: dma_buf_release+0x2c/0x254 drivers/dma-buf/dma-buf.c:88 __dentry_kill+0x294/0x31c fs/dcache.c:584 dentry_kill fs/dcache.c:673 [inline] dput+0x250/0x380 fs/dcache.c:859 path_put+0x24/0x40 fs/namei.c:485 alloc_file_pseudo+0x1a4/0x200 fs/file_table.c:235 dma_buf_getfile drivers/dma-buf/dma-buf.c:473 [inline] dma_buf_export+0x25c/0x3ec drivers/dma-buf/dma-buf.c:585 Fix this by checking for the valid pointer in the dentry->d_fsdata. Fixes: 4ab59c3 ("dma-buf: Move dma_buf_release() from fops to dentry_ops") Cc: <[email protected]> [5.7+] Signed-off-by: Charan Teja Reddy <[email protected]> Reviewed-by: Christian König <[email protected]> Link: https://patchwork.freedesktop.org/patch/391319/ Signed-off-by: Christian König <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> Signed-off-by: Paolo Pisati <[email protected]>
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