linux-stable.git/lib/scatterlist.c, branch v3.16.78

lib/scatterlist: Fix mapping iterator when sg->offset is greater than PAGE_SIZE

2019-10-31T22:15:01+00:00

commit aeb87246537a83c2aff482f3f34a2e0991e02cbc upstream.

All mapping iterator logic is based on the assumption that sg->offset
is always lower than PAGE_SIZE.

But there are situations where sg->offset is such that the SG item
is on the second page. In that case sg_copy_to_buffer() fails
properly copying the data into the buffer. One of the reason is
that the data will be outside the kmapped area used to access that
data.

This patch fixes the issue by adjusting the mapping iterator
offset and pgoffset fields such that offset is always lower than
PAGE_SIZE.

Signed-off-by: Christophe Leroy 
Fixes: 4225fc8555a9 ("lib/scatterlist: use page iterator in the mapping iterator")
Signed-off-by: Herbert Xu 
Signed-off-by: Ben Hutchings

lib/scatterlist: export sg_miter_skip()

2013-12-09T01:56:37+00:00

sg_copy_buffer() can't meet demand for some drrivers(such usb
mass storage), so we have to use the sg_miter_* APIs to access
sg buffer, then need export sg_miter_skip() for these drivers.

The API is needed for converting to sg_miter_* APIs in USB storage
driver for accessing sg buffer.

Acked-by: Andrew Morton 
Cc: FUJITA Tomonori 
Cc: Jens Axboe 
Signed-off-by: Ming Lei 
Reviewed-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman

lib/scatterlist.c: don't flush_kernel_dcache_page on slab page

2013-10-31T23:58:13+00:00

Commit b1adaf65ba03 ("[SCSI] block: add sg buffer copy helper
functions") introduces two sg buffer copy helpers, and calls
flush_kernel_dcache_page() on pages in SG list after these pages are
written to.

Unfortunately, the commit may introduce a potential bug:

 - Before sending some SCSI commands, kmalloc() buffer may be passed to
   block layper, so flush_kernel_dcache_page() can see a slab page
   finally

 - According to cachetlb.txt, flush_kernel_dcache_page() is only called
   on "a user page", which surely can't be a slab page.

 - ARCH's implementation of flush_kernel_dcache_page() may use page
   mapping information to do optimization so page_mapping() will see the
   slab page, then VM_BUG_ON() is triggered.

Aaro Koskinen reported the bug on ARM/kirkwood when DEBUG_VM is enabled,
and this patch fixes the bug by adding test of '!PageSlab(miter->page)'
before calling flush_kernel_dcache_page().

Signed-off-by: Ming Lei 
Reported-by: Aaro Koskinen 
Tested-by: Simon Baatz 
Cc: Russell King - ARM Linux 
Cc: Will Deacon 
Cc: Aaro Koskinen 
Acked-by: Catalin Marinas 
Cc: FUJITA Tomonori 
Cc: Tejun Heo 
Cc: "James E.J. Bottomley" 
Cc: Jens Axboe 
Cc: 	[3.2+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

lib/scatterlist: error handling in __sg_alloc_table()

2013-07-09T17:33:31+00:00

I was reviewing code which I suspected might allocate a zero size SG
table.  That will cause memory corruption.  Also we can't return before
doing the memset or we could end up using uninitialized memory in the
cleanup path.

Signed-off-by: Dan Carpenter 
Cc: Akinobu Mita 
Cc: Imre Deak 
Cc: Tejun Heo 
Cc: Daniel Vetter 
Cc: Maxim Levitsky 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

lib/scatterlist: introduce sg_pcopy_from_buffer() and sg_pcopy_to_buffer()

2013-07-09T17:33:30+00:00

The only difference between sg_pcopy_{from,to}_buffer() and
sg_copy_{from,to}_buffer() is an additional argument that specifies the
number of bytes to skip the SG list before copying.

Signed-off-by: Akinobu Mita 
Cc: "David S. Miller" 
Cc: "James E.J. Bottomley" 
Cc: Douglas Gilbert 
Cc: Herbert Xu 
Cc: Horia Geanta 
Cc: Imre Deak 
Acked-by: Tejun Heo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

lib/scatterlist: factor out sg_miter_get_next_page() from sg_miter_next()

2013-07-09T17:33:30+00:00

This patchset introduces sg_pcopy_from_buffer() and sg_pcopy_to_buffer(),
which copy data between a linear buffer and an SG list.

The only difference between sg_pcopy_{from,to}_buffer() and
sg_copy_{from,to}_buffer() is an additional argument that specifies the
number of bytes to skip the SG list before copying.

The main reason for introducing these functions is to fix a problem in
scsi_debug module.  And there is a local function in crypto/talitos
module, which can be replaced by sg_pcopy_to_buffer().

This patch:

sg_miter_get_next_page() is used to proceed page iterator to the next page
if necessary, and will be used to implement the variants of
sg_copy_{from,to}_buffer() later.

Signed-off-by: Akinobu Mita 
Acked-by: Tejun Heo 
Cc: Tejun Heo 
Cc: Imre Deak 
Cc: Herbert Xu 
Cc: "David S. Miller" 
Cc: "James E.J. Bottomley" 
Cc: Douglas Gilbert 
Cc: Horia Geanta 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

lib/scatterlist: sg_page_iter: support sg lists w/o backing pages

2013-03-27T16:13:44+00:00

The i915 driver uses sg lists for memory without backing 'struct page'
pages, similarly to other IO memory regions, setting only the DMA
address for these. It does this, so that it can program the HW MMU
tables in a uniform way both for sg lists with and without backing pages.

Without a valid page pointer we can't call nth_page to get the current
page in __sg_page_iter_next, so add a helper that relevant users can
call separately. Also add a helper to get the DMA address of the current
page (idea from Daniel).

Convert all places in i915, to use the new API.

Signed-off-by: Imre Deak 
Reviewed-by: Damien Lespiau 
Signed-off-by: Daniel Vetter

lib/scatterlist: use page iterator in the mapping iterator

2013-02-28T03:10:10+00:00

For better code reuse use the newly added page iterator to iterate
through the pages.  The offset, length within the page is still
calculated by the mapping iterator as well as the actual mapping.  Idea
from Tejun Heo.

Signed-off-by: Imre Deak 
Cc: Maxim Levitsky 
Cc: Tejun Heo 
Cc: Daniel Vetter 
Cc: James Hogan 
Cc: Stephen Warren 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

lib/scatterlist: add simple page iterator

2013-02-28T03:10:10+00:00

Add an iterator to walk through a scatter list a page at a time starting
at a specific page offset.  As opposed to the mapping iterator this is
meant to be small, performing well even in simple loops like collecting
all pages on the scatterlist into an array or setting up an iommu table
based on the pages' DMA address.

Signed-off-by: Imre Deak 
Cc: Maxim Levitsky 
Cc: Tejun Heo 
Cc: Daniel Vetter 
Tested-by: Stephen Warren 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

scatterlist: don't BUG when we can trivially return a proper error.

2012-12-18T01:15:28+00:00

There is absolutely no reason to crash the kernel when we have a
perfectly good return value already available to use for conveying
failure status.

Let's return an error code instead of crashing the kernel: that sounds
like a much better plan.

[akpm@linux-foundation.org: s/E2BIG/EINVAL/]
Signed-off-by: Nick Bowler 
Cc: Maxim Levitsky 
Cc: Tejun Heo 
Cc: Jens Axboe 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds