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authorJ. Bruce Fields <bfields@citi.umich.edu>2007-03-21 08:50:12 +1100
committerHerbert Xu <herbert@gondor.apana.org.au>2007-03-21 08:50:12 +1100
commitf70ee5ec8fc59ba2d905e6daf0d395edf6fb461d (patch)
treebfa4a0f71f0e11187775f5f8c53e2a8afbb673ce /crypto/scatterwalk.c
parent5851fadce8824d5d4b8fd02c22ae098401f6489e (diff)
downloadlinux-f70ee5ec8fc59ba2d905e6daf0d395edf6fb461d.tar.gz
[CRYPTO] api: scatterwalk_copychunks() fails to advance through scatterlist
In the loop in scatterwalk_copychunks(), if walk->offset is zero, then scatterwalk_pagedone rounds that up to the nearest page boundary: walk->offset += PAGE_SIZE - 1; walk->offset &= PAGE_MASK; which is a no-op in this case, so we don't advance to the next element of the scatterlist array: if (walk->offset >= walk->sg->offset + walk->sg->length) scatterwalk_start(walk, sg_next(walk->sg)); and we end up copying the same data twice. It appears that other callers of scatterwalk_{page}done first advance walk->offset, so I believe that's the correct thing to do here. This caused a bug in NFS when run with krb5p security, which would cause some writes to fail with permissions errors--for example, writes of less than 8 bytes (the des blocksize) at the start of a file. A git-bisect shows the bug was originally introduced by 5c64097aa0f6dc4f27718ef47ca9a12538d62860, first in 2.6.19-rc1. Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto/scatterwalk.c')
-rw-r--r--crypto/scatterwalk.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
index 35172d3f043..a6642312177 100644
--- a/crypto/scatterwalk.c
+++ b/crypto/scatterwalk.c
@@ -91,6 +91,8 @@ void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
memcpy_dir(buf, vaddr, len_this_page, out);
scatterwalk_unmap(vaddr, out);
+ scatterwalk_advance(walk, nbytes);
+
if (nbytes == len_this_page)
break;
@@ -99,7 +101,5 @@ void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
scatterwalk_pagedone(walk, out, 1);
}
-
- scatterwalk_advance(walk, nbytes);
}
EXPORT_SYMBOL_GPL(scatterwalk_copychunks);