diff options
Diffstat (limited to 'target/linux/generic/backport-5.10/633-v6.3-skbuff-Fix-a-race-between-coalescing-and-releasing-S.patch')
| -rw-r--r-- | target/linux/generic/backport-5.10/633-v6.3-skbuff-Fix-a-race-between-coalescing-and-releasing-S.patch | 85 |
1 files changed, 0 insertions, 85 deletions
diff --git a/target/linux/generic/backport-5.10/633-v6.3-skbuff-Fix-a-race-between-coalescing-and-releasing-S.patch b/target/linux/generic/backport-5.10/633-v6.3-skbuff-Fix-a-race-between-coalescing-and-releasing-S.patch deleted file mode 100644 index 2ad315d7f9..0000000000 --- a/target/linux/generic/backport-5.10/633-v6.3-skbuff-Fix-a-race-between-coalescing-and-releasing-S.patch +++ /dev/null @@ -1,85 +0,0 @@ -From: Liang Chen <liangchen.linux@gmail.com> -Date: Thu, 13 Apr 2023 17:03:53 +0800 -Subject: [PATCH] skbuff: Fix a race between coalescing and releasing SKBs - -Commit 1effe8ca4e34 ("skbuff: fix coalescing for page_pool fragment -recycling") allowed coalescing to proceed with non page pool page and page -pool page when @from is cloned, i.e. - -to->pp_recycle --> false -from->pp_recycle --> true -skb_cloned(from) --> true - -However, it actually requires skb_cloned(@from) to hold true until -coalescing finishes in this situation. If the other cloned SKB is -released while the merging is in process, from_shinfo->nr_frags will be -set to 0 toward the end of the function, causing the increment of frag -page _refcount to be unexpectedly skipped resulting in inconsistent -reference counts. Later when SKB(@to) is released, it frees the page -directly even though the page pool page is still in use, leading to -use-after-free or double-free errors. So it should be prohibited. - -The double-free error message below prompted us to investigate: -BUG: Bad page state in process swapper/1 pfn:0e0d1 -page:00000000c6548b28 refcount:-1 mapcount:0 mapping:0000000000000000 -index:0x2 pfn:0xe0d1 -flags: 0xfffffc0000000(node=0|zone=1|lastcpupid=0x1fffff) -raw: 000fffffc0000000 0000000000000000 ffffffff00000101 0000000000000000 -raw: 0000000000000002 0000000000000000 ffffffffffffffff 0000000000000000 -page dumped because: nonzero _refcount - -CPU: 1 PID: 0 Comm: swapper/1 Tainted: G E 6.2.0+ -Call Trace: - <IRQ> -dump_stack_lvl+0x32/0x50 -bad_page+0x69/0xf0 -free_pcp_prepare+0x260/0x2f0 -free_unref_page+0x20/0x1c0 -skb_release_data+0x10b/0x1a0 -napi_consume_skb+0x56/0x150 -net_rx_action+0xf0/0x350 -? __napi_schedule+0x79/0x90 -__do_softirq+0xc8/0x2b1 -__irq_exit_rcu+0xb9/0xf0 -common_interrupt+0x82/0xa0 -</IRQ> -<TASK> -asm_common_interrupt+0x22/0x40 -RIP: 0010:default_idle+0xb/0x20 - -Fixes: 53e0961da1c7 ("page_pool: add frag page recycling support in page pool") -Signed-off-by: Liang Chen <liangchen.linux@gmail.com> -Reviewed-by: Eric Dumazet <edumazet@google.com> -Link: https://lore.kernel.org/r/20230413090353.14448-1-liangchen.linux@gmail.com -Signed-off-by: Jakub Kicinski <kuba@kernel.org> ---- - ---- a/net/core/skbuff.c -+++ b/net/core/skbuff.c -@@ -5208,18 +5208,18 @@ bool skb_try_coalesce(struct sk_buff *to - if (skb_cloned(to)) - return false; - -- /* In general, avoid mixing slab allocated and page_pool allocated -- * pages within the same SKB. However when @to is not pp_recycle and -- * @from is cloned, we can transition frag pages from page_pool to -- * reference counted. -- * -- * On the other hand, don't allow coalescing two pp_recycle SKBs if -- * @from is cloned, in case the SKB is using page_pool fragment -+ /* In general, avoid mixing page_pool and non-page_pool allocated -+ * pages within the same SKB. Additionally avoid dealing with clones -+ * with page_pool pages, in case the SKB is using page_pool fragment - * references (PP_FLAG_PAGE_FRAG). Since we only take full page - * references for cloned SKBs at the moment that would result in - * inconsistent reference counts. -+ * In theory we could take full references if @from is cloned and -+ * !@to->pp_recycle but its tricky (due to potential race with -+ * the clone disappearing) and rare, so not worth dealing with. - */ -- if (to->pp_recycle != (from->pp_recycle && !skb_cloned(from))) -+ if (to->pp_recycle != from->pp_recycle || -+ (from->pp_recycle && skb_cloned(from))) - return false; - - if (len <= skb_tailroom(to)) { |