| Message ID | 20200229231120.1147527-1-nivedita@alum.mit.edu (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86/mm/init: Stop printing pgt_buf addresses | expand |
On Sat, Feb 29, 2020 at 06:11:20PM -0500, Arvind Sankar wrote: > This currently leaks kernel physical addresses into userspace. > > Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Acked-by: Kees Cook <keescook@chromium.org> -Kees > --- > arch/x86/mm/init.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > index e7bb483557c9..dc4711f09cdc 100644 > --- a/arch/x86/mm/init.c > +++ b/arch/x86/mm/init.c > @@ -121,8 +121,6 @@ __ref void *alloc_low_pages(unsigned int num) > } else { > pfn = pgt_buf_end; > pgt_buf_end += num; > - printk(KERN_DEBUG "BRK [%#010lx, %#010lx] PGTABLE\n", > - pfn << PAGE_SHIFT, (pgt_buf_end << PAGE_SHIFT) - 1); > } > > for (i = 0; i < num; i++) { > -- > 2.24.1 >
On Sat, Feb 29, 2020 at 06:11:20PM -0500, Arvind Sankar wrote: > This currently leaks kernel physical addresses into userspace. > > Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> > --- > arch/x86/mm/init.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > index e7bb483557c9..dc4711f09cdc 100644 > --- a/arch/x86/mm/init.c > +++ b/arch/x86/mm/init.c > @@ -121,8 +121,6 @@ __ref void *alloc_low_pages(unsigned int num) > } else { > pfn = pgt_buf_end; > pgt_buf_end += num; > - printk(KERN_DEBUG "BRK [%#010lx, %#010lx] PGTABLE\n", > - pfn << PAGE_SHIFT, (pgt_buf_end << PAGE_SHIFT) - 1); > } > > for (i = 0; i < num; i++) { > -- > 2.24.1 > This was acked by Kees, is it ok for merge? Thanks.
On 4/9/20 3:19 PM, Arvind Sankar wrote: >> @@ -121,8 +121,6 @@ __ref void *alloc_low_pages(unsigned int num) >> } else { >> pfn = pgt_buf_end; >> pgt_buf_end += num; >> - printk(KERN_DEBUG "BRK [%#010lx, %#010lx] PGTABLE\n", >> - pfn << PAGE_SHIFT, (pgt_buf_end << PAGE_SHIFT) - 1); >> } >> >> for (i = 0; i < num; i++) { >> -- >> 2.24.1 >> > This was acked by Kees, is it ok for merge? Independent of the obvious security implications, I don't think I've ever once gleaned useful information from that message. It's fine by me. Acked-by: Dave Hansen <dave.hansen@intel.com>
On Sat, Feb 29, 2020 at 06:11:20PM -0500, Arvind Sankar wrote: > This currently leaks kernel physical addresses into userspace. > > Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> > --- > arch/x86/mm/init.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > index e7bb483557c9..dc4711f09cdc 100644 > --- a/arch/x86/mm/init.c > +++ b/arch/x86/mm/init.c > @@ -121,8 +121,6 @@ __ref void *alloc_low_pages(unsigned int num) > } else { > pfn = pgt_buf_end; > pgt_buf_end += num; > - printk(KERN_DEBUG "BRK [%#010lx, %#010lx] PGTABLE\n", > - pfn << PAGE_SHIFT, (pgt_buf_end << PAGE_SHIFT) - 1); > } > > for (i = 0; i < num; i++) { > -- > 2.24.1 > Ping. https://lore.kernel.org/lkml/20200229231120.1147527-1-nivedita@alum.mit.edu/
On Fri, 2020-05-22 at 21:51 -0400, Arvind Sankar wrote: > On Sat, Feb 29, 2020 at 06:11:20PM -0500, Arvind Sankar wrote: > > This currently leaks kernel physical addresses into userspace. > > > > Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> > > --- > > arch/x86/mm/init.c | 2 -- > > 1 file changed, 2 deletions(-) > > > > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > > index e7bb483557c9..dc4711f09cdc 100644 > > --- a/arch/x86/mm/init.c > > +++ b/arch/x86/mm/init.c > > @@ -121,8 +121,6 @@ __ref void *alloc_low_pages(unsigned int num) > > } else { > > pfn = pgt_buf_end; > > pgt_buf_end += num; > > - printk(KERN_DEBUG "BRK [%#010lx, %#010lx] PGTABLE\n", > > - pfn << PAGE_SHIFT, (pgt_buf_end << PAGE_SHIFT) - 1); > > } > > > > for (i = 0; i < num; i++) { > > -- > > 2.24.1 > > > > Ping. > > https://lore.kernel.org/lkml/20200229231120.1147527-1-nivedita@alum.mit.edu/ If this output is at all valuable, perhaps emit them as hashed pointers? Maybe: --- arch/x86/mm/init.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 1bba16c5742b..44f0d6592c7e 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -121,8 +121,9 @@ __ref void *alloc_low_pages(unsigned int num) } else { pfn = pgt_buf_end; pgt_buf_end += num; - printk(KERN_DEBUG "BRK [%#010lx, %#010lx] PGTABLE\n", - pfn << PAGE_SHIFT, (pgt_buf_end << PAGE_SHIFT) - 1); + printk(KERN_DEBUG "BRK [0x%8p, 0x%8p] PGTABLE\n", + (void *)(pfn << PAGE_SHIFT), + (void *)((pgt_buf_end << PAGE_SHIFT) - 1)); } for (i = 0; i < num; i++) {
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index e7bb483557c9..dc4711f09cdc 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -121,8 +121,6 @@ __ref void *alloc_low_pages(unsigned int num) } else { pfn = pgt_buf_end; pgt_buf_end += num; - printk(KERN_DEBUG "BRK [%#010lx, %#010lx] PGTABLE\n", - pfn << PAGE_SHIFT, (pgt_buf_end << PAGE_SHIFT) - 1); } for (i = 0; i < num; i++) {
This currently leaks kernel physical addresses into userspace. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> --- arch/x86/mm/init.c | 2 -- 1 file changed, 2 deletions(-)