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Commit 46963e2e authored by Mathias Krause's avatar Mathias Krause Committed by Greg Kroah-Hartman
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misc: fastrpc: avoid double fput() on failed usercopy



If the copy back to userland fails for the FASTRPC_IOCTL_ALLOC_DMA_BUFF
ioctl(), we shouldn't assume that 'buf->dmabuf' is still valid. In fact,
dma_buf_fd() called fd_install() before, i.e. "consumed" one reference,
leaving us with none.

Calling dma_buf_put() will therefore put a reference we no longer own,
leading to a valid file descritor table entry for an already released
'file' object which is a straight use-after-free.

Simply avoid calling dma_buf_put() and rely on the process exit code to
do the necessary cleanup, if needed, i.e. if the file descriptor is
still valid.

Fixes: 6cffd795 ("misc: fastrpc: Add support for dmabuf exporter")
Acked-by: default avatarChristian König <christian.koenig@amd.com>
Signed-off-by: default avatarMathias Krause <minipli@grsecurity.net>
Link: https://lore.kernel.org/r/20220127130218.809261-1-minipli@grsecurity.net


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 26291c54
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