From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neftin, Sasha Date: Wed, 6 Apr 2022 17:33:35 +0300 Subject: [Intel-wired-lan] [PATCH v2 1/1] e1000e: Fix possible overflow in LTR decoding In-Reply-To: References: <20220405155601.1443799-1-sasha.neftin@intel.com> Message-ID: <46988714-070b-fca0-efe8-52004649976a@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: On 4/6/2022 08:34, Paul Menzel wrote: > Dear Sasha, > > > Thank you for your patch. > > Am 05.04.22 um 17:56 schrieb Sasha Neftin: >> When we decode the latency and the max_latency u16 value does not fill >> the required size > > Do you mean ?fit into? or ?is too small for the required size?? > >> and could lead to the wrong LTR representation. > > Maybe give an example of values leading to incorrect behavior? > >> Replace the u16 type with the u32 type and allow corrected LTR >> representation. > > Maybe: Increase the variable size from u16 to u32, so the decoded > latency can be represented. Why are 32 bit enough? Why not 64 bit? Hello Paul, Scaling represented as: scale 0 - 1 (2^(5*0)) = 2^0 scale 1 - 32 (2^(5 *1))= 2^5 scale 2 - 1024 (2^(5 *2)) =2^10 scale 3 - 32768 (2^(5 *3)) =2^15 scale 4 ? 1048576 (2^(5 *4)) = 2^20 scale 5 ? 33554432 (2^(5 *4)) = 2^25 scale 4 and scale 5 required 20 and 25 bits respectively. scale 6 reserved. > > Please use 75 characters per line. > >> Fixes: 44a13a5d99c7 ("e1000e: Fix the max snoop/no-snoop latency for >> 10M") >> Reported-by: James Hutchinson >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=215689 >> Suggested-by: Dima Ruinskiy >> Signed-off-by: Sasha Neftin > > Add > > Tested-by: James Hutchinson (I219-V (rev > 30)) I will let James add this tag. > >> --- >> v2: added link tag >> >> ? drivers/net/ethernet/intel/e1000e/ich8lan.c | 4 ++-- >> ? 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.c >> b/drivers/net/ethernet/intel/e1000e/ich8lan.c >> index d60e2016d03c..e6c8e6d5234f 100644 >> --- a/drivers/net/ethernet/intel/e1000e/ich8lan.c >> +++ b/drivers/net/ethernet/intel/e1000e/ich8lan.c >> @@ -1009,8 +1009,8 @@ static s32 e1000_platform_pm_pch_lpt(struct >> e1000_hw *hw, bool link) >> ? { >> ????? u32 reg = link << (E1000_LTRV_REQ_SHIFT + >> E1000_LTRV_NOSNOOP_SHIFT) | >> ????????? link << E1000_LTRV_REQ_SHIFT | E1000_LTRV_SEND; >> -??? u16 max_ltr_enc_d = 0;??? /* maximum LTR decoded by platform */ >> -??? u16 lat_enc_d = 0;??? /* latency decoded */ >> +??? u32 max_ltr_enc_d = 0;??? /* maximum LTR decoded by platform */ >> +??? u32 lat_enc_d = 0;??? /* latency decoded */ >> ????? u16 lat_enc = 0;??? /* latency encoded */ >> ????? if (link) { > > The diff looks good. Thanks > > > Kind regards, > > Paul Sasha