>From 00a22f2f1e34ba0765ca49120499e681477a265a Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Wed, 22 Jul 2009 08:36:22 -0400 Subject: [PATCH] fix offset checks in do_sendfile to use unsigned values (try #2) This is the second version of this patch. Some of the checks do need to use signed values. This patch should be more correct in that regard. This also adds a check to make sure that "pos + count" doesn't overflow. If do_sendfile is called with a "max" value of 0, it grabs the lesser s_maxbytes value of the two superblocks to use instead. There's a problem here however. s_maxbytes is an unsigned long long and it gets cast to a signed value. If both s_maxbytes values are large enough, max will end up being negative and the comparisons in this code won't work correctly. Change do_sendfile to use unsigned values internally for the offset checks against "max". Signed-off-by: Jeff Layton --- fs/read_write.c | 21 ++++++++++++--------- 1 files changed, 12 insertions(+), 9 deletions(-) diff --git a/fs/read_write.c b/fs/read_write.c index 6c8c55d..2c5b402 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -788,11 +788,11 @@ SYSCALL_DEFINE5(pwritev, unsigned long, fd, const struct iovec __user *, vec, } static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos, - size_t count, loff_t max) + size_t count, unsigned long long max) { struct file * in_file, * out_file; struct inode * in_inode, * out_inode; - loff_t pos; + unsigned long long pos, newpos; ssize_t retval; int fput_needed_in, fput_needed_out, fl; @@ -835,14 +835,16 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos, goto fput_out; count = retval; - if (!max) - max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes); - - pos = *ppos; retval = -EINVAL; - if (unlikely(pos < 0)) + if (unlikely(*ppos < 0)) goto fput_out; - if (unlikely(pos + count > max)) { + + if (!max) + max = min(in_inode->i_sb->s_maxbytes, + out_inode->i_sb->s_maxbytes); + pos = (unsigned long long) *ppos; + newpos = pos + count; + if (unlikely(newpos > max || newpos < count)) { retval = -EOVERFLOW; if (pos >= max) goto fput_out; @@ -869,7 +871,8 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos, inc_syscr(current); inc_syscw(current); - if (*ppos > max) + pos = (unsigned long long) *ppos; + if (pos > max) retval = -EOVERFLOW; fput_out: -- 1.6.2.5