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[ Upstream commit 1aedcafbf32b3f232c159b14cd0d423fcfe2b861 ] Use BUG_ON(in_interrupt()) in zs_map_object(). This is not a new BUG_ON(), it's always been there, but was recently changed to VM_BUG_ON(). There are several problems there. First, we use use per-CPU mappings both in zsmalloc and in zram, and interrupt may easily corrupt those buffers. Second, and more importantly, we believe it's possible to start leaking sensitive information. Consider the following case: -> process P swap out zram per-cpu mapping CPU1 compress page A -> IRQ swap out zram per-cpu mapping CPU1 compress page B write page from per-cpu mapping CPU1 to zsmalloc pool iret -> process P write page from per-cpu mapping CPU1 to zsmalloc pool [*] return * so we store overwritten data that actually belongs to another page (task) and potentially contains sensitive data. And when process P will page fault it's going to read (swap in) that other task's data. Link: http://lkml.kernel.org/r/20170929045140.4055-1-sergey.senozhatsky@gmail.com Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.