> -----Original Message----- > From: Luis Henriques [mailto:luis.henriques@xxxxxxxxxxxxx] > Sent: Wednesday, April 10, 2013 8:18 AM > To: Lingzhu Xiang > Cc: Ben Hutchings; Seiji Aguchi; linux-kernel@xxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx; kernel-team@xxxxxxxxxxxxxxxx; Matthew > Garrett; Josh Boyer; Michael Schroeder; Lee, Chun-Yi; Matt Fleming > Subject: Re: [PATCH 097/102] efivars: explicitly calculate length of VariableName > > On Wed, Apr 10, 2013 at 06:27:13PM +0800, Lingzhu Xiang wrote: > > On 04/10/2013 06:45 AM, Ben Hutchings wrote: > > >On Mon, 2013-04-08 at 10:50 +0100, Luis Henriques wrote: > > >>3.5.7.10 -stable review patch. If anyone has any objections, please let me know. > > >> > > >>------------------ > > >> > > >>From: Matt Fleming <matt.fleming@xxxxxxxxx> > > >> > > >>commit ec50bd32f1672d38ddce10fb1841cbfda89cfe9a upstream. > > >> > > >>It's not wise to assume VariableNameSize represents the length of > > >>VariableName, as not all firmware updates VariableNameSize in the > > >>same way (some don't update it at all if EFI_SUCCESS is returned). > > >>There are even implementations out there that update > > >>VariableNameSize with values that are both larger than the string > > >>returned in VariableName and smaller than the buffer passed to > > >>GetNextVariableName(), which resulted in the following bug report > > >>from Michael Schroeder, > > >> > > >> > On HP z220 system (firmware version 1.54), some EFI variables are > > >> > incorrectly named : > > >> > > > >> > ls -d /sys/firmware/efi/vars/*8be4d* | grep -v -- -8be returns > > >> > /sys/firmware/efi/vars/dbxDefault-pport8be4df61-93ca-11d2-aa0d-00e098032b8c > > >> > /sys/firmware/efi/vars/KEKDefault-pport8be4df61-93ca-11d2-aa0d-00e098032b8c > > >> > /sys/firmware/efi/vars/SecureBoot-pport8be4df61-93ca-11d2-aa0d-00e098032b8c > > >> > > > >> /sys/firmware/efi/vars/SetupMode-Information8be4df61-93ca-11d2-aa0d > > >> -00e098032b8c > > >> > > >>The issue here is that because we blindly use VariableNameSize > > >>without verifying its value, we can potentially read garbage values > > >>from the buffer containing VariableName if VariableNameSize is > > >>larger than the length of VariableName. > > >> > > >>Since VariableName is a string, we can calculate its size by > > >>searching for the terminating NULL character. > > >> > > >>Reported-by: Frederic Crozat <fcrozat@xxxxxxxx> > > >>Cc: Matthew Garrett <mjg59@xxxxxxxxxxxxx> > > >>Cc: Josh Boyer <jwboyer@xxxxxxxxxx> > > >>Cc: Michael Schroeder <mls@xxxxxxxx> > > >>Cc: Lee, Chun-Yi <jlee@xxxxxxxx> > > >>Cc: Lingzhu Xiang <lxiang@xxxxxxxxxx> > > >>Cc: Seiji Aguchi <seiji.aguchi@xxxxxxx> > > >>Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx> [ Backported > > >>for 3.4-stable. Removed workqueue code added in a93bc0c 3.9-rc1. ] > > >[...] > > > > > >I thought the workqueue addition was a worthwhile fix in its own > > >right, so for 3.2.y I cherry-picked that as well. > > > > FWIW, the workqueue patch is 1/2 of this patchset[1] fixing closely > > related problems. The other one is 81fa4e58. > > > > [1]: http://article.gmane.org/gmane.linux.kernel/1439570 > > > > I tried to avoid pulling too much for stable because the patchset is > > quite large and I suspect the problem it fixes is only theoretical. > > I reported the original bug but was unable to break anything except > > getting call traces with various CONFIG_DEBUG_*. > > > > What's your opinion, Seiji? > > Ok, so just to clarify: you're suggesting me to pick the following commits: > > 81fa4e581d9283f7992a0d8c534bb141eb840a14 efivars: Disable external interrupt while holding efivars->lock > a93bc0c6e07ed9bac44700280e65e2945d864fd4 efi_pstore: Introducing workqueue updating sysfs > ec50bd32f1672d38ddce10fb1841cbfda89cfe9a efivars: explicitly calculate length of VariableName > e971318bbed610e28bb3fde9d548e6aaf0a6b02e efivars: Handle duplicate names from get_next_variable() I agree to add these commits to a stable tree. Seiji > > Is this correct? > > Cheers, > -- > Luis -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html