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3f084a4d28
commit26b5b874afupstream. As Al Viro noted in commit128394eff3("sg_write()/bsg_write() is not fit to be called under KERNEL_DS"), sg improperly accesses userspace memory outside the provided buffer, permitting kernel memory corruption via splice(). But it doesn't just do it on ->write(), also on ->read(). As a band-aid, make sure that the ->read() and ->write() handlers can not be called in weird contexts (kernel context or credentials different from file opener), like for ib_safe_file_access(). If someone needs to use these interfaces from different security contexts, a new interface should be written that goes through the ->ioctl() handler. I've mostly copypasted ib_safe_file_access() over as sg_safe_file_access() because I couldn't find a good common header - please tell me if you know a better way. [mkp: s/_safe_/_check_/] Fixes:1da177e4c3("Linux-2.6.12-rc2") Signed-off-by: Jann Horn <jannh@google.com> Acked-by: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> [bwh: Backported to 3.16: open-code uaccess_kernel()] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2683 lines
71 KiB
2683 lines
71 KiB