batman-adv: frag: ensure fragment is writable before modifying TTL

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commit b7293c6e8c upstream.

Before batman-adv is allowed to write to an skb, it either has to have its
own copy of the skb or use skb_cow() to ensure that the data part is not
shared. But batadv_frag_skb_fwd() modifies the TTL even when it is shared.

Adding a skb_cow() right before this operation avoids this and can at the
same time prepare it for the modifications required to forward the
fragment.

Cc: stable@kernel.org
Fixes: 610bfc6bc9 ("batman-adv: Receive fragmented packets and merge")
[ Context ]
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Sven Eckelmann 2026-06-26 18:10:53 +02:00 • committed by Greg Kroah-Hartman

parent 701f4333ca

commit 595e6bcf36

3 changed files with 17 additions and 4 deletions

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15

net/batman-adv/fragmentation.c

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3

net/batman-adv/fragmentation.h

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3

net/batman-adv/routing.c

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