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fuse: don't overflow LLONG_MAX with end offset 

Handle the special case of fuse_readpages() wanting to read the last page
of a hugest file possible and overflowing the end offset in the process.

This is basically to unbreak xfstests:generic/525 and prevent filesystems
from doing bad things with an overflowing offset.

Reported-by: Xiao Yang <ice_yangxiao@163.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi 2020-02-06 16:39:28 +01:00
parent f658adeea4
commit 2f1398291b
1 changed files with 12 additions and 0 deletions
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12
fs/fuse/file.c
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@ -803,6 +803,10 @@ static int fuse_do_readpage(struct file *file, struct page *page)
attr_ver = fuse_get_attr_version(fc);
/* Don't overflow end offset */
if (pos + (desc.length - 1) == LLONG_MAX)
desc.length--;
fuse_read_args_fill(&ia, file, pos, desc.length, FUSE_READ);
res = fuse_simple_request(fc, &ia.ap.args);
if (res < 0)
@ -888,6 +892,14 @@ static void fuse_send_readpages(struct fuse_io_args *ia, struct file *file)
ap->args.out_pages = true;
ap->args.page_zeroing = true;
ap->args.page_replace = true;
/* Don't overflow end offset */
if (pos + (count - 1) == LLONG_MAX) {
count--;
ap->descs[ap->num_pages - 1].length--;
}
WARN_ON((loff_t) (pos + count) < 0);
fuse_read_args_fill(ia, file, pos, count, FUSE_READ);
ia->read.attr_ver = fuse_get_attr_version(fc);
if (fc->async_read) {