CVE request: kernel: fuse: prevent fuse_put_request on invalid pointer

[Eugene Teo <eugeneteo () kernel sg>]

"fuse_direct_io() has a loop where requests are allocated in each 
iteration. if allocation fails, the loop is broken out and follows into 
an unconditional fuse_put_request() on that invalid pointer."

Upstream commit:
http://git.kernel.org/linus/f60311d5f7670d9539b424e4ed8b5c0872fc9e83

This can be triggered when the system is low on memory, and when the 
fuse_request_alloc() function called from fuse_get_req() fails. The 
fuse_put_request() function will then dereference the invalid pointer 
returned, resulting in a kernel oops.

This was introduced in 413ef8cb (v2.6.14-rc1) and fixed in v2.6.32-rc7.

https://bugzilla.redhat.com/538734

Thanks, Eugene