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authorAl Viro <viro@ZenIV.linux.org.uk>2014-01-17 07:53:39 -0500
committerSteven Rostedt <rostedt@goodmis.org>2014-01-19 16:53:13 -0500
commit92fdd98cf8bdec4d6b0c510e2f073ac4fd059be8 (patch)
tree0b8a7946835eb969ea2e8fcf335be2f119f696be /include/trace
parentdced341b2d4f06668efaab33f88de5d287c0f45b (diff)
tracing: Fix buggered tee(2) on tracing_pipe
In kernel/trace/trace.c we have this: static void tracing_pipe_buf_release(struct pipe_inode_info *pipe, struct pipe_buffer *buf) { __free_page(buf->page); } static const struct pipe_buf_operations tracing_pipe_buf_ops = { .can_merge = 0, .map = generic_pipe_buf_map, .unmap = generic_pipe_buf_unmap, .confirm = generic_pipe_buf_confirm, .release = tracing_pipe_buf_release, .steal = generic_pipe_buf_steal, .get = generic_pipe_buf_get, }; with void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) { page_cache_get(buf->page); } and I don't see anything that would've prevented tee(2) called on the pipe that got stuff spliced into it from that sucker. ->ops->get() will be called, then buf gets copied into target pipe's ->bufs[] and eventually readers get to both copies of the buffer. With get_page(page) look at that page __free_page(page) look at that page __free_page(page) which is not a good thing, to put it mildly. AFAICS, that ought to use the normal generic_pipe_buf_release() (aka page_cache_release(buf->page)), shouldn't it? [ SDR - As trace_pipe just allocates the page with alloc_page(GFP_KERNEL), and doesn't do anything special with it (no LRU logic). The __free_page() should be fine, as it wont actually free a page with reference count. Maybe there's a chance to leak memory? Anyway, This change is at a minimum good for being symmetric with generic_pipe_buf_get, it is fine to add. ] Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> [ SDR - Removed no longer used tracing_pipe_buf_release ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'include/trace')
0 files changed, 0 insertions, 0 deletions

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