Revision 6b3a707736301c2128ca85ce85fb13f60b5e350a authored by Linus Torvalds on 14 April 2019, 22:09:40 UTC, committed by Linus Torvalds on 14 April 2019, 22:09:40 UTC
Merge page ref overflow branch. Jann Horn reported that he can overflow the page ref count with sufficient memory (and a filesystem that is intentionally extremely slow). Admittedly it's not exactly easy. To have more than four billion references to a page requires a minimum of 32GB of kernel memory just for the pointers to the pages, much less any metadata to keep track of those pointers. Jann needed a total of 140GB of memory and a specially crafted filesystem that leaves all reads pending (in order to not ever free the page references and just keep adding more). Still, we have a fairly straightforward way to limit the two obvious user-controllable sources of page references: direct-IO like page references gotten through get_user_pages(), and the splice pipe page duplication. So let's just do that. * branch page-refs: fs: prevent page refcount overflow in pipe_buf_get mm: prevent get_user_pages() from overflowing page refcount mm: add 'try_get_page()' helper function mm: make page ref count overflow check tighter and more explicit
File | Mode | Size |
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Kconfig | -rw-r--r-- | 65.1 KB |
Makefile | -rw-r--r-- | 1.2 KB |
calibrate.c | -rw-r--r-- | 8.6 KB |
do_mounts.c | -rw-r--r-- | 15.1 KB |
do_mounts.h | -rw-r--r-- | 1.1 KB |
do_mounts_initrd.c | -rw-r--r-- | 3.5 KB |
do_mounts_md.c | -rw-r--r-- | 7.9 KB |
do_mounts_rd.c | -rw-r--r-- | 8.1 KB |
init_task.c | -rw-r--r-- | 5.2 KB |
initramfs.c | -rw-r--r-- | 13.7 KB |
main.c | -rw-r--r-- | 28.9 KB |
noinitramfs.c | -rw-r--r-- | 1.5 KB |
version.c | -rw-r--r-- | 1.2 KB |
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