kernel/linux.git/lib/iov_iter.c, branch v5.10.257

mm/highmem: Lift memcpy_[to|from]_page to core

2023-01-14T09:16:42+00:00

[ Upstream commit bb90d4bc7b6a536b2e4db45f4763e467c2008251 ] Working through a conversion to a call kmap_local_page() instead of kmap() revealed many places where the pattern kmap/memcpy/kunmap occurred. Eric Biggers, Matthew Wilcox, Christoph Hellwig, Dan Williams, and Al Viro all suggested putting this code into helper functions. Al Viro further pointed out that these functions already existed in the iov_iter code.[1] Various locations for the lifted functions were considered. Headers like mm.h or string.h seem ok but don't really portray the functionality well. pagemap.h made some sense but is for page cache functionality.[2] Another alternative would be to create a new header for the promoted memcpy functions, but it masks the fact that these are designed to copy to/from pages using the kernel direct mappings and complicates matters with a new header. Placing these functions in 'highmem.h' is suboptimal especially with the changes being proposed in the functionality of kmap. From a caller perspective including/using 'highmem.h' implies that the functions defined in that header are only required when highmem is in use which is increasingly not the case with modern processors. However, highmem.h is where all the current functions like this reside (zero_user(), clear_highpage(), clear_user_highpage(), copy_user_highpage(), and copy_highpage()). So it makes the most sense even though it is distasteful for some.[3] Lift memcpy_to_page() and memcpy_from_page() to pagemap.h. [1] https://lore.kernel.org/lkml/20201013200149.GI3576660@ZenIV.linux.org.uk/ https://lore.kernel.org/lkml/20201013112544.GA5249@infradead.org/ [2] https://lore.kernel.org/lkml/20201208122316.GH7338@casper.infradead.org/ [3] https://lore.kernel.org/lkml/20201013200149.GI3576660@ZenIV.linux.org.uk/#t https://lore.kernel.org/lkml/20201208163814.GN1563847@iweiny-DESK2.sc.intel.com/ Cc: Boris Pismenny Cc: Or Gerlitz Cc: Dave Hansen Suggested-by: Matthew Wilcox Suggested-by: Christoph Hellwig Suggested-by: Dan Williams Suggested-by: Al Viro Suggested-by: Eric Biggers Reviewed-by: Chaitanya Kulkarni Reviewed-by: Christoph Hellwig Signed-off-by: Ira Weiny Signed-off-by: David Sterba Stable-dep-of: 956510c0c743 ("fs: ext4: initialize fsdata in pagecache_write()") Signed-off-by: Sasha Levin

iov_iter: add helper to save iov_iter state

2023-01-04T10:39:16+00:00

[ Upstream commit 8fb0f47a9d7acf620d0fd97831b69da9bc5e22ed ] In an ideal world, when someone is passed an iov_iter and returns X bytes, then X bytes would have been consumed/advanced from the iov_iter. But we have use cases that always consume the entire iterator, a few examples of that are iomap and bdev O_DIRECT. This means we cannot rely on the state of the iov_iter once we've called ->read_iter() or ->write_iter(). This would be easier if we didn't always have to deal with truncate of the iov_iter, as rewinding would be trivial without that. We recently added a commit to track the truncate state, but that grew the iov_iter by 8 bytes and wasn't the best solution. Implement a helper to save enough of the iov_iter state to sanely restore it after we've called the read/write iterator helpers. This currently only works for IOVEC/BVEC/KVEC as that's all we need, support for other iterator types are left as an exercise for the reader. Link: https://lore.kernel.org/linux-fsdevel/CAHk-=wiacKV4Gh-MYjteU0LwNBSGpWrK-Ov25HdqB1ewinrFPg@mail.gmail.com/ Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

lib/iov_iter: initialize "flags" in new pipe_buffer

2022-02-23T11:01:06+00:00

commit 9d2231c5d74e13b2a0546fee6737ee4446017903 upstream. The functions copy_page_to_iter_pipe() and push_pipe() can both allocate a new pipe_buffer, but the "flags" member initializer is missing. Fixes: 241699cd72a8 ("new iov_iter flavour: pipe-backed") To: Alexander Viro To: linux-fsdevel@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Max Kellermann Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman

iov_iter: Fix iov_iter_get_pages{,_alloc} page fault return value

2021-11-18T13:03:57+00:00

[ Upstream commit 814a66741b9ffb5e1ba119e368b178edb0b7322d ] Both iov_iter_get_pages and iov_iter_get_pages_alloc return the number of bytes of the iovec they could get the pages for. When they cannot get any pages, they're supposed to return 0, but when the start of the iovec isn't page aligned, the calculation goes wrong and they return a negative value. Fix both functions. In addition, change iov_iter_get_pages_alloc to return NULL in that case to prevent resource leaks. Signed-off-by: Andreas Gruenbacher Reviewed-by: Christoph Hellwig Signed-off-by: Sasha Levin

iov_iter_fault_in_readable() should do nothing in xarray case

2021-07-14T14:55:39+00:00

commit 0e8f0d67401589a141950856902c7d0ec8d9c985 upstream. ... and actually should just check it's given an iovec-backed iterator in the first place. Cc: stable@vger.kernel.org Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman

copy_page_to_iter(): fix ITER_DISCARD case

2021-07-14T14:55:39+00:00

commit a506abc7b644d71966a75337d5a534f531b3cdc4 upstream. we need to advance the iterator... Cc: stable@vger.kernel.org Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman

udp: fix skb_copy_and_csum_datagram with odd segment sizes

2021-02-17T10:02:28+00:00

commit 52cbd23a119c6ebf40a527e53f3402d2ea38eccb upstream. When iteratively computing a checksum with csum_block_add, track the offset "pos" to correctly rotate in csum_block_add when offset is odd. The open coded implementation of skb_copy_and_csum_datagram did this. With the switch to __skb_datagram_iter calling csum_and_copy_to_iter, pos was reinitialized to 0 on each call. Bring back the pos by passing it along with the csum to the callback. Changes v1->v2 - pass csum value, instead of csump pointer (Alexander Duyck) Link: https://lore.kernel.org/netdev/20210128152353.GB27281@optiplex/ Fixes: 950fcaecd5cc ("datagram: consolidate datagram copy to iter helpers") Reported-by: Oliver Graute Signed-off-by: Willem de Bruijn Reviewed-by: Alexander Duyck Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20210203192952.1849843-1-willemdebruijn.kernel@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

iov_iter: fix the uaccess area in copy_compat_iovec_from_user

2021-01-27T10:55:09+00:00

[ Upstream commit a959a9782fa87669feeed095ced5d78181a7c02d ] sizeof needs to be called on the compat pointer, not the native one. Fixes: 89cd35c58bc2 ("iov_iter: transparently handle compat iovecs in import_iovec") Reported-by: David Laight Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro Signed-off-by: Sasha Levin

lib, uaccess: add failure injection to usercopy functions

2020-10-16T18:11:22+00:00

To test fault-tolerance of user memory access functions, introduce fault injection to usercopy functions. If a failure is expected return either -EFAULT or the total amount of bytes that were not copied. Signed-off-by: Albert van der Linde Signed-off-by: Andrew Morton Reviewed-by: Akinobu Mita Reviewed-by: Alexander Potapenko Cc: Al Viro Cc: Andrey Konovalov Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Dmitry Vyukov Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Marco Elver Cc: Peter Zijlstra (Intel) Cc: Thomas Gleixner Cc: Christoph Hellwig Link: http://lkml.kernel.org/r/20200831171733.955393-3-alinde@google.com Signed-off-by: Linus Torvalds

Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2020-10-12T23:35:51+00:00

Pull compat iovec cleanups from Al Viro: "Christoph's series around import_iovec() and compat variant thereof" * 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: security/keys: remove compat_keyctl_instantiate_key_iov mm: remove compat_process_vm_{readv,writev} fs: remove compat_sys_vmsplice fs: remove the compat readv/writev syscalls fs: remove various compat readv/writev helpers iov_iter: transparently handle compat iovecs in import_iovec iov_iter: refactor rw_copy_check_uvector and import_iovec iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c compat.h: fix a spelling error in