@@ -1884,7 +1884,13 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
struct btrfs_log_ctx ctx;
int ret = 0;
bool full_sync = 0;
+ u64 len;
+ /*
+ * The range length can be represented by u64, we have to do the typecasts
+ * to avoid signed overflow if it's [0, LLONG_MAX] eg. from fsync()
+ */
+ len = (u64)end - (u64)start + 1;
trace_btrfs_sync_file(file, datasync);
/*
@@ -1912,7 +1918,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
* all extents are persisted and the respective file extent
* items are in the fs/subvol btree.
*/
- ret = btrfs_wait_ordered_range(inode, start, end - start + 1);
+ ret = btrfs_wait_ordered_range(inode, start, len);
} else {
/*
* Start any new ordered operations before starting to log the
@@ -2070,8 +2076,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
}
}
if (!full_sync) {
- ret = btrfs_wait_ordered_range(inode, start,
- end - start + 1);
+ ret = btrfs_wait_ordered_range(inode, start, len);
if (ret) {
btrfs_end_transaction(trans, root);
goto out;
This is a note to let you know that I have just added a patch titled btrfs: fix signed overflows in btrfs_sync_file to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.8-ckt12. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 4a3fc9135df21adc22c290d3224d8d2e8adc7bbc Mon Sep 17 00:00:00 2001 From: David Sterba <dsterba@suse.com> Date: Mon, 9 Nov 2015 11:44:45 +0100 Subject: btrfs: fix signed overflows in btrfs_sync_file commit 9dcbeed4d7e11e1dcf5e55475de3754f0855d1c2 upstream. The calculation of range length in btrfs_sync_file leads to signed overflow. This was caught by PaX gcc SIZE_OVERFLOW plugin. https://forums.grsecurity.net/viewtopic.php?f=1&t=4284 The fsync call passes 0 and LLONG_MAX, the range length does not fit to loff_t and overflows, but the value is converted to u64 so it silently works as expected. The minimal fix is a typecast to u64, switching functions to take (start, end) instead of (start, len) would be more intrusive. Coccinelle script found that there's one more opencoded calculation of the length. <smpl> @@ loff_t start, end; @@ * end - start </smpl> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Chris Mason <clm@fb.com> [ kamal: backport to 3.19-stable: use len in both btrfs_wait_ordered_range calls, like b659ef0 Btrfs: avoid syncing log in the fast fsync path when not necessary ] Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- fs/btrfs/file.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) -- 1.9.1