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Subject[PATCH 2/4] vfs: explicitly cast s_maxbytes in fiemap_check_ranges
Date
If fiemap_check_ranges is passed a large enough value, then it's
possible that the value would be cast to a signed value for comparison
against s_maxbytes when we change it to loff_t. Make sure that doesn't
happen by explicitly casting s_maxbytes to an unsigned value for the
purposes of comparison.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
fs/ioctl.c | 9 +++++----
1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 5612880..7b17a14 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -162,20 +162,21 @@ EXPORT_SYMBOL(fiemap_check_flags);
static int fiemap_check_ranges(struct super_block *sb,
u64 start, u64 len, u64 *new_len)
{
+ u64 maxbytes = (u64) sb->s_maxbytes;
+
*new_len = len;

if (len == 0)
return -EINVAL;

- if (start > sb->s_maxbytes)
+ if (start > maxbytes)
return -EFBIG;

/*
* Shrink request scope to what the fs can actually handle.
*/
- if ((len > sb->s_maxbytes) ||
- (sb->s_maxbytes - len) < start)
- *new_len = sb->s_maxbytes - start;
+ if (len > maxbytes || (maxbytes - len) < start)
+ *new_len = maxbytes - start;

return 0;
}
--
1.6.0.6


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