From eaa2f87c6b840b83827c40db6eb8481689570259 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Fri, 18 Aug 2017 13:30:30 +0300 Subject: x86/ldt: Fix off by one in get_segment_base() ldt->entries[] is allocated in alloc_ldt_struct(). It has ldt->nr_entries elements and ldt->nr_entries is capped at LDT_ENTRIES. So if "idx" is == ldt->nr_entries then we're reading beyond the end of the buffer. It seems duplicative to have two limit checks when one would work just as well so I removed the check against LDT_ENTRIES. The gdt_page.gdt[] array has GDT_ENTRIES entries. Signed-off-by: Dan Carpenter Acked-by: Andy Lutomirski Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: kernel-janitors@vger.kernel.org Fixes: d07bdfd322d3 ("perf/x86: Fix USER/KERNEL tagging of samples properly") Link: http://lkml.kernel.org/r/20170818102516.gqwm4xdvvuvjw5ho@mwanda Signed-off-by: Ingo Molnar --- arch/x86/events/core.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index af12e294caed..939050169d12 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2335,12 +2335,9 @@ static unsigned long get_segment_base(unsigned int segment) #ifdef CONFIG_MODIFY_LDT_SYSCALL struct ldt_struct *ldt; - if (idx > LDT_ENTRIES) - return 0; - /* IRQs are off, so this synchronizes with smp_store_release */ ldt = lockless_dereference(current->active_mm->context.ldt); - if (!ldt || idx > ldt->nr_entries) + if (!ldt || idx >= ldt->nr_entries) return 0; desc = &ldt->entries[idx]; @@ -2348,7 +2345,7 @@ static unsigned long get_segment_base(unsigned int segment) return 0; #endif } else { - if (idx > GDT_ENTRIES) + if (idx >= GDT_ENTRIES) return 0; desc = raw_cpu_ptr(gdt_page.gdt) + idx; -- cgit v1.2.3 From 5746f0555d00e1cbb7bc20a2fd09041ace6f350c Mon Sep 17 00:00:00 2001 From: "Jan H. Schönherr" Date: Sun, 27 Aug 2017 15:55:24 +0200 Subject: x86/boot: Provide more slack space during decompression MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The current slack space is not enough for LZ4, which has a worst case overhead of 0.4% for data that cannot be further compressed. With an LZ4 compressed kernel with an embedded initrd, the output is likely to overwrite the input. Increase the slack space to avoid that. Signed-off-by: Jan H. Schönherr Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1503842124-29718-1-git-send-email-jschoenh@amazon.de Signed-off-by: Ingo Molnar --- arch/x86/boot/header.S | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S index 2ed8f0c25def..1bb08ecffd24 100644 --- a/arch/x86/boot/header.S +++ b/arch/x86/boot/header.S @@ -520,8 +520,14 @@ pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr # the description in lib/decompressor_xxx.c for specific information. # # extra_bytes = (uncompressed_size >> 12) + 65536 + 128 +# +# LZ4 is even worse: data that cannot be further compressed grows by 0.4%, +# or one byte per 256 bytes. OTOH, we can safely get rid of the +128 as +# the size-dependent part now grows so fast. +# +# extra_bytes = (uncompressed_size >> 8) + 65536 -#define ZO_z_extra_bytes ((ZO_z_output_len >> 12) + 65536 + 128) +#define ZO_z_extra_bytes ((ZO_z_output_len >> 8) + 65536) #if ZO_z_output_len > ZO_z_input_len # define ZO_z_extract_offset (ZO_z_output_len + ZO_z_extra_bytes - \ ZO_z_input_len) -- cgit v1.2.3 From fb1cc2f91664fd8a2e454970480b5413725919f1 Mon Sep 17 00:00:00 2001 From: "Jan H. Schönherr" Date: Sun, 27 Aug 2017 20:23:43 +0200 Subject: x86/boot: Prevent faulty bootparams.screeninfo from causing harm MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If a zero for the number of lines manages to slip through, scroll() may underflow some offset calculations, causing accesses outside the video memory. Make the check in __putstr() more pessimistic to prevent that. Signed-off-by: Jan H. Schönherr Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1503858223-14983-1-git-send-email-jschoenh@amazon.de Signed-off-by: Ingo Molnar --- arch/x86/boot/compressed/misc.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index a0838ab929f2..c14217cd0155 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -116,8 +116,7 @@ void __putstr(const char *s) } } - if (boot_params->screen_info.orig_video_mode == 0 && - lines == 0 && cols == 0) + if (lines == 0 || cols == 0) return; x = boot_params->screen_info.orig_x; -- cgit v1.2.3