musl: Fix CVE-2019-14697
authorHauke Mehrtens <hauke@hauke-m.de>
Sun, 18 Aug 2019 21:24:43 +0000 (23:24 +0200)
committerHauke Mehrtens <hauke@hauke-m.de>
Sun, 18 Aug 2019 21:59:23 +0000 (23:59 +0200)
musl libc through 1.1.23 has an x87 floating-point stack adjustment
imbalance, related to the math/i386/ directory. In some cases, use of
this library could introduce out-of-bounds writes that are not present
in an application's source code.

This problem only affects x86 and no other architectures.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
\ 2(cherry picked from commit c262daf308e0f0bd93bb5c5ee6238773935079ee)

toolchain/musl/common.mk
toolchain/musl/patches/030-fix-x87-stack-imbalance-in-corner-cases-of-i386-math.patch [new file with mode: 0644]
toolchain/musl/patches/031-fix-build-regression-in-i386-asm-for-atan2-atan2f.patch [new file with mode: 0644]

index 433ca21..bb93b7b 100644 (file)
@@ -9,7 +9,7 @@ include $(INCLUDE_DIR)/target.mk
 
 PKG_NAME:=musl
 PKG_VERSION:=1.1.23
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_SUBDIR:=$(PKG_NAME)-$(PKG_VERSION)
diff --git a/toolchain/musl/patches/030-fix-x87-stack-imbalance-in-corner-cases-of-i386-math.patch b/toolchain/musl/patches/030-fix-x87-stack-imbalance-in-corner-cases-of-i386-math.patch
new file mode 100644 (file)
index 0000000..a709330
--- /dev/null
@@ -0,0 +1,179 @@
+From f3ed8bfe8a82af1870ddc8696ed4cc1d5aa6b441 Mon Sep 17 00:00:00 2001
+From: Rich Felker <dalias@aerifal.cx>
+Date: Mon, 5 Aug 2019 18:41:47 -0400
+Subject: fix x87 stack imbalance in corner cases of i386 math asm
+
+commit 31c5fb80b9eae86f801be4f46025bc6532a554c5 introduced underflow
+code paths for the i386 math asm, along with checks on the fpu status
+word to skip the underflow-generation instructions if the underflow
+flag was already raised. unfortunately, at least one such path, in
+log1p, returned with 2 items on the x87 stack rather than just 1 item
+for the return value. this is a violation of the ABI's calling
+convention, and could cause subsequent floating point code to produce
+NANs due to x87 stack overflow. if floating point results are used in
+flow control, this can lead to runaway wrong code execution.
+
+rather than reviewing each "underflow already raised" code path for
+correctness, remove them all. they're likely slower than just
+performing the underflow code unconditionally, and significantly more
+complex.
+
+all of this code should be ripped out and replaced by C source files
+with inline asm. doing so would preclude this kind of error by having
+the compiler perform all x87 stack register allocation and stack
+manipulation, and would produce comparable or better code. however
+such a change is a much larger project.
+---
+ src/math/i386/asin.s   | 10 ++--------
+ src/math/i386/atan.s   |  7 ++-----
+ src/math/i386/atan2.s  |  5 +----
+ src/math/i386/atan2f.s |  5 +----
+ src/math/i386/atanf.s  |  7 ++-----
+ src/math/i386/exp.s    | 10 ++--------
+ src/math/i386/log1p.s  |  7 ++-----
+ src/math/i386/log1pf.s |  7 ++-----
+ 8 files changed, 14 insertions(+), 44 deletions(-)
+
+--- a/src/math/i386/asin.s
++++ b/src/math/i386/asin.s
+@@ -7,13 +7,10 @@ asinf:
+       cmp $0x01000000,%eax
+       jae 1f
+               # subnormal x, return x with underflow
+-      fnstsw %ax
+-      and $16,%ax
+-      jnz 2f
+       fld %st(0)
+       fmul %st(1)
+       fstps 4(%esp)
+-2:    ret
++      ret
+ .global asinl
+ .type asinl,@function
+@@ -30,11 +27,8 @@ asin:
+       cmp $0x00200000,%eax
+       jae 1f
+               # subnormal x, return x with underflow
+-      fnstsw %ax
+-      and $16,%ax
+-      jnz 2f
+       fsts 4(%esp)
+-2:    ret
++      ret
+ 1:    fld %st(0)
+       fld1
+       fsub %st(0),%st(1)
+--- a/src/math/i386/atan.s
++++ b/src/math/i386/atan.s
+@@ -10,8 +10,5 @@ atan:
+       fpatan
+       ret
+               # subnormal x, return x with underflow
+-1:    fnstsw %ax
+-      and $16,%ax
+-      jnz 2f
+-      fsts 4(%esp)
+-2:    ret
++1:    fsts 4(%esp)
++      ret
+--- a/src/math/i386/atan2.s
++++ b/src/math/i386/atan2.s
+@@ -10,8 +10,5 @@ atan2:
+       cmp $0x00200000,%eax
+       jae 1f
+               # subnormal x, return x with underflow
+-      fnstsw %ax
+-      and $16,%ax
+-      jnz 1f
+       fsts 4(%esp)
+-1:    ret
++      ret
+--- a/src/math/i386/atan2f.s
++++ b/src/math/i386/atan2f.s
+@@ -10,10 +10,7 @@ atan2f:
+       cmp $0x01000000,%eax
+       jae 1f
+               # subnormal x, return x with underflow
+-      fnstsw %ax
+-      and $16,%ax
+-      jnz 1f
+       fld %st(0)
+       fmul %st(1)
+       fstps 4(%esp)
+-1:    ret
++      ret
+--- a/src/math/i386/atanf.s
++++ b/src/math/i386/atanf.s
+@@ -10,10 +10,7 @@ atanf:
+       fpatan
+       ret
+               # subnormal x, return x with underflow
+-1:    fnstsw %ax
+-      and $16,%ax
+-      jnz 2f
+-      fld %st(0)
++1:    fld %st(0)
+       fmul %st(1)
+       fstps 4(%esp)
+-2:    ret
++      ret
+--- a/src/math/i386/exp.s
++++ b/src/math/i386/exp.s
+@@ -7,13 +7,10 @@ expm1f:
+       cmp $0x01000000,%eax
+       jae 1f
+               # subnormal x, return x with underflow
+-      fnstsw %ax
+-      and $16,%ax
+-      jnz 2f
+       fld %st(0)
+       fmul %st(1)
+       fstps 4(%esp)
+-2:    ret
++      ret
+ .global expm1l
+ .type expm1l,@function
+@@ -30,11 +27,8 @@ expm1:
+       cmp $0x00200000,%eax
+       jae 1f
+               # subnormal x, return x with underflow
+-      fnstsw %ax
+-      and $16,%ax
+-      jnz 2f
+       fsts 4(%esp)
+-2:    ret
++      ret
+ 1:    fldl2e
+       fmulp
+       mov $0xc2820000,%eax
+--- a/src/math/i386/log1p.s
++++ b/src/math/i386/log1p.s
+@@ -16,9 +16,6 @@ log1p:
+       fyl2x
+       ret
+               # subnormal x, return x with underflow
+-2:    fnstsw %ax
+-      and $16,%ax
+-      jnz 1f
+-      fsts 4(%esp)
++2:    fsts 4(%esp)
+       fstp %st(1)
+-1:    ret
++      ret
+--- a/src/math/i386/log1pf.s
++++ b/src/math/i386/log1pf.s
+@@ -16,10 +16,7 @@ log1pf:
+       fyl2x
+       ret
+               # subnormal x, return x with underflow
+-2:    fnstsw %ax
+-      and $16,%ax
+-      jnz 1f
+-      fxch
++2:    fxch
+       fmul %st(1)
+       fstps 4(%esp)
+-1:    ret
++      ret
diff --git a/toolchain/musl/patches/031-fix-build-regression-in-i386-asm-for-atan2-atan2f.patch b/toolchain/musl/patches/031-fix-build-regression-in-i386-asm-for-atan2-atan2f.patch
new file mode 100644 (file)
index 0000000..8c5161b
--- /dev/null
@@ -0,0 +1,28 @@
+From 6818c31c9bc4bbad5357f1de14bedf781e5b349e Mon Sep 17 00:00:00 2001
+From: Rich Felker <dalias@aerifal.cx>
+Date: Mon, 5 Aug 2019 19:57:07 -0400
+Subject: fix build regression in i386 asm for atan2, atan2f
+
+commit f3ed8bfe8a82af1870ddc8696ed4cc1d5aa6b441 inadvertently removed
+labels that were still needed.
+---
+ src/math/i386/atan2.s  | 2 +-
+ src/math/i386/atan2f.s | 2 +-
+ 2 files changed, 2 insertions(+), 2 deletions(-)
+
+--- a/src/math/i386/atan2.s
++++ b/src/math/i386/atan2.s
+@@ -11,4 +11,4 @@ atan2:
+       jae 1f
+               # subnormal x, return x with underflow
+       fsts 4(%esp)
+-      ret
++1:    ret
+--- a/src/math/i386/atan2f.s
++++ b/src/math/i386/atan2f.s
+@@ -13,4 +13,4 @@ atan2f:
+       fld %st(0)
+       fmul %st(1)
+       fstps 4(%esp)
+-      ret
++1:    ret