Commit ddd0a42671 only increments scomp_scratch_users when it was 0,
causing a panic when using ipcomp:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 UID: 0 PID: 619 Comm: ping Tainted: G N 6.15.0-rc3-net-00032-ga79be02bba5c #41 PREEMPT(full)
Tainted: [N]=TEST
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014
RIP: 0010:inflate_fast+0x5a2/0x1b90
[...]
Call Trace:
<IRQ>
zlib_inflate+0x2d60/0x6620
deflate_sdecompress+0x166/0x350
scomp_acomp_comp_decomp+0x45f/0xa10
scomp_acomp_decompress+0x21/0x120
acomp_do_req_chain+0x3e5/0x4e0
ipcomp_input+0x212/0x550
xfrm_input+0x2de2/0x72f0
[...]
Kernel panic - not syncing: Fatal exception in interrupt
Kernel Offset: disabled
---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---
Instead, let's keep the old increment, and decrement back to 0 if the
scratch allocation fails.
Fixes: ddd0a42671 ("crypto: scompress - Fix scratch allocation failure handling")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
a32f1923c6