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authorDavid Sterba <dsterba@suse.com>2015-11-09 13:44:45 +0300
committerChris Mason <clm@fb.com>2015-11-25 16:19:50 +0300
commit9dcbeed4d7e11e1dcf5e55475de3754f0855d1c2 (patch)
tree4f1418f234da7f11144e2d512b681f004926440a /fs
parentd5f2e33b92b10b8007be50b570a27e9bacfb4c3a (diff)
downloadlinux-9dcbeed4d7e11e1dcf5e55475de3754f0855d1c2.tar.xz
btrfs: fix signed overflows in btrfs_sync_file
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> CC: stable@vger.kernel.org Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/file.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 3009d4536d38..8eb1f3c1b647 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1882,8 +1882,13 @@ 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;
- const u64 len = end - start + 1;
+ 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);
/*
@@ -2071,8 +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;