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Message-ID: <CAGXu5jK=JhBFHBGpbWF46DC3-QMruiB0qqz1z+njcK2h7jVU9w@mail.gmail.com> Date: Thu, 8 Mar 2018 11:52:25 -0800 From: Kees Cook <keescook@...omium.org> To: Stephen Kitt <steve@....org> Cc: hare <hare@...e.com>, linux-scsi@...r.kernel.org, Kernel Hardening <kernel-hardening@...ts.openwall.com>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] aic7xxx/aic79xx: remove VLAs On Thu, Mar 8, 2018 at 5:22 AM, Stephen Kitt <steve@....org> wrote: > In preparation to enabling -Wvla, remove VLAs and replace them with > fixed-length arrays instead. > > The arrays fixed here, using the number of constant sections, aren't > really VLAs, but they appear so to the compiler. Since we know at > build-time how many critical sections there are, we might as well use > a pre-processor-level constant instead. > > This was prompted by https://lkml.org/lkml/2018/3/7/621 > > Signed-off-by: Stephen Kitt <steve@....org> > --- > drivers/scsi/aic7xxx/aic79xx_core.c | 8 ++++---- > drivers/scsi/aic7xxx/aic79xx_seq.h_shipped | 3 +-- > drivers/scsi/aic7xxx/aic7xxx_core.c | 8 ++++---- > drivers/scsi/aic7xxx/aic7xxx_seq.h_shipped | 3 +-- > drivers/scsi/aic7xxx/aicasm/aicasm.c | 6 ++++-- > 5 files changed, 14 insertions(+), 14 deletions(-) > > diff --git a/drivers/scsi/aic7xxx/aic79xx_core.c b/drivers/scsi/aic7xxx/aic79xx_core.c > index b560f396ee99..034f4eebb160 100644 > --- a/drivers/scsi/aic7xxx/aic79xx_core.c > +++ b/drivers/scsi/aic7xxx/aic79xx_core.c > @@ -9338,9 +9338,9 @@ ahd_dumpseq(struct ahd_softc* ahd) > static void > ahd_loadseq(struct ahd_softc *ahd) > { > - struct cs cs_table[num_critical_sections]; > - u_int begin_set[num_critical_sections]; > - u_int end_set[num_critical_sections]; > + struct cs cs_table[NUM_CRITICAL_SECTIONS]; > + u_int begin_set[NUM_CRITICAL_SECTIONS]; > + u_int end_set[NUM_CRITICAL_SECTIONS]; > const struct patch *cur_patch; > u_int cs_count; > u_int cur_cs; > @@ -9456,7 +9456,7 @@ ahd_loadseq(struct ahd_softc *ahd) > * Move through the CS table until we find a CS > * that might apply to this instruction. > */ > - for (; cur_cs < num_critical_sections; cur_cs++) { > + for (; cur_cs < NUM_CRITICAL_SECTIONS; cur_cs++) { > if (critical_sections[cur_cs].end <= i) { > if (begin_set[cs_count] == TRUE > && end_set[cs_count] == FALSE) { > diff --git a/drivers/scsi/aic7xxx/aic79xx_seq.h_shipped b/drivers/scsi/aic7xxx/aic79xx_seq.h_shipped > index 4b51e232392f..20fb9ca9e271 100644 > --- a/drivers/scsi/aic7xxx/aic79xx_seq.h_shipped > +++ b/drivers/scsi/aic7xxx/aic79xx_seq.h_shipped > @@ -1186,5 +1186,4 @@ static const struct cs { > { 759, 763 } > }; > > -static const int num_critical_sections = sizeof(critical_sections) > - / sizeof(*critical_sections); > +#define NUM_CRITICAL_SECTIONS 14 The compiler doesn't treat "const" as a literal, hence the need to change this. However, you can still use the sizeof (actually, this is exactly ARRAY_SIZE()). Perhaps: #define NUM_CRITICAL_SECTIONS ARRAY_SIZE(critical_sections) ? Otherwise, looks great! -Kees -- Kees Cook Pixel Security
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