From 2d4b49864eba70606b1bee3d0a3e8414189dcd6d Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Mon, 10 May 2021 09:56:43 +0930 Subject: [PATCH] Avoid possible pointer wrap PTR supplied to these macros can be read from user input, END is an end of buffer pointer. It's safer to do arithmetic on END than on PTR. * dwarf.c (SAFE_BYTE_GET): Check bounds by subtracting amount from END rather than adding amount to PTR. (SAFE_SIGNED_BYTE_GET, SAFE_BYTE_GET64): Likewise. --- binutils/ChangeLog | 6 ++++++ binutils/dwarf.c | 6 +++--- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/binutils/ChangeLog b/binutils/ChangeLog index 302629794c0..ae27252e982 100644 --- a/binutils/ChangeLog +++ b/binutils/ChangeLog @@ -1,3 +1,9 @@ +2021-05-10 Alan Modra + + * dwarf.c (SAFE_BYTE_GET): Check bounds by subtracting amount from + END rather than adding amount to PTR. + (SAFE_SIGNED_BYTE_GET, SAFE_BYTE_GET64): Likewise. + 2021-05-09 Alan Modra * objcopy.c (eq_string): Delete. diff --git a/binutils/dwarf.c b/binutils/dwarf.c index d93d9239684..c584f5b2a24 100644 --- a/binutils/dwarf.c +++ b/binutils/dwarf.c @@ -406,7 +406,7 @@ read_leb128 (unsigned char *data, amount, (int) sizeof (VAL)); \ amount = sizeof (VAL); \ } \ - if (((PTR) + amount) >= (END)) \ + if ((PTR) >= (END) - amount) \ { \ if ((PTR) < (END)) \ amount = (END) - (PTR); \ @@ -434,7 +434,7 @@ read_leb128 (unsigned char *data, do \ { \ unsigned int amount = (AMOUNT); \ - if (((PTR) + amount) >= (END)) \ + if ((PTR) >= (END) - amount) \ { \ if ((PTR) < (END)) \ amount = (END) - (PTR); \ @@ -460,7 +460,7 @@ read_leb128 (unsigned char *data, #define SAFE_BYTE_GET64(PTR, HIGH, LOW, END) \ do \ { \ - if (((PTR) + 8) <= (END)) \ + if ((PTR) <= (END) - 8) \ { \ byte_get_64 ((PTR), (HIGH), (LOW)); \ } \ -- 2.30.2