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| author | Jeongjun Park <aha310510@gmail.com> | 2025-01-11 01:26:12 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-02-17 10:04:49 +0100 |
| commit | 22a1a758183da84ad1ef7cd68beb45932fe8cbc9 (patch) | |
| tree | 6dc453e6f082e7c72ac6942b76bd6d2ba0fed290 /kernel | |
| parent | d1544dc32c67c80b9e3512fa4e187931be1a9e8c (diff) | |
| download | linux-22a1a758183da84ad1ef7cd68beb45932fe8cbc9.tar.gz linux-22a1a758183da84ad1ef7cd68beb45932fe8cbc9.tar.bz2 linux-22a1a758183da84ad1ef7cd68beb45932fe8cbc9.zip | |
ring-buffer: Make reading page consistent with the code logic
[ Upstream commit 6e31b759b076eebb4184117234f0c4eb9e4bc460 ]
In the loop of __rb_map_vma(), the 's' variable is calculated from the
same logic that nr_pages is and they both come from nr_subbufs. But the
relationship is not obvious and there's a WARN_ON_ONCE() around the 's'
variable to make sure it never becomes equal to nr_subbufs within the
loop. If that happens, then the code is buggy and needs to be fixed.
The 'page' variable is calculated from cpu_buffer->subbuf_ids[s] which is
an array of 'nr_subbufs' entries. If the code becomes buggy and 's'
becomes equal to or greater than 'nr_subbufs' then this will be an out of
bounds hit before the WARN_ON() is triggered and the code exiting safely.
Make the 'page' initialization consistent with the code logic and assign
it after the out of bounds check.
Link: https://lore.kernel.org/20250110162612.13983-1-aha310510@gmail.com
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
[ sdr: rewrote change log ]
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/ring_buffer.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 703978b2d557..28fad7bcfcf8 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -7059,7 +7059,7 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, } while (p < nr_pages) { - struct page *page = virt_to_page((void *)cpu_buffer->subbuf_ids[s]); + struct page *page; int off = 0; if (WARN_ON_ONCE(s >= nr_subbufs)) { @@ -7067,6 +7067,8 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *cpu_buffer, goto out; } + page = virt_to_page((void *)cpu_buffer->subbuf_ids[s]); + for (; off < (1 << (subbuf_order)); off++, page++) { if (p >= nr_pages) break; |