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Mon, 10 Aug 2020 15:24:46 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1597065887; bh=I/Sx/HdpIxh4i9UsobCMs9UPgI56qxrzVMpyXIjjkEc=; h=X-UI-Sender-Class:From:To:Cc:Subject:Date:In-Reply-To:References; b=QUGz5PdoKSGFSh5g2NcspKqIguTDf5/TPb3Fv9vL2khrXbD8bfkujnvwdjTPpe/AM 7kZiO/CJDoYQ66neLDip4Rzkb1aIDGTfMog0GFL0/mh6OyMulJRWDjRnhGEN2wozTb mbCWeULOBhhSjHyCYFnAfMgMFKAGFta8prgqDVvg= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c From: Helge Deller To: peter.maydell@linaro.org, qemu-devel@nongnu.org Subject: [PULL v2 07/12] hw/display/artist: Refactor artist_rop8() to avoid buffer over-run Date: Mon, 10 Aug 2020 15:24:36 +0200 Message-Id: <20200810132441.16551-8-deller@gmx.de> X-Mailer: git-send-email 2.21.3 In-Reply-To: <20200810132441.16551-1-deller@gmx.de> References: <20200810132441.16551-1-deller@gmx.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:RBu5uyb0LyB0fIjkGoRK+8FIq++UNiCPVdyM4IdmGZLULo/w7gf FK5j3GqW9v7KhapleBxE/vRZY8f7J+OtDG4iWS+amk1FNUdW39CsmIgRWyfAoF/Km8KGB9u i5qJePyGKiPXb7ileYsgU266Wd6ACFm9AcNF3m1xM3ekrljSbR3GWKHqv686WzM7vIfefxl nw0VcCBXc2y2tePlSrXJg== X-UI-Out-Filterresults: notjunk:1;V03:K0:WNSW+elqNjQ=:10J1AmZlGAi02C34ET5y1o urno0IEZgWy1vbREuo1T2XGfqr5obtgIv9dr0hSiXhf1Q7EgKqcHH+VFXvOWGLWWT0D9iA2Xb DC5q6wVasgTGPgPRDvNOeNtNse/70RCeWzAFXix0gUDjlVkDsRDixTG4NbLorG1vWFA4E1RlJ TN5E9YU52oZo4t03c9fJ09R5F6tl583hi1IivNkVwrIhqaL6mOBT9ABaHdvhr2feEHmv5T2Si IBFofSRLYNeH3xdQ6gw+rD1lN8ic+LGy+wnr71yqAOolhP61fg/+m9Loqznt1ccqYT5tpKUQ/ Cqw1yql2DvanxlO0aDy3c5wKhvXZckml4tThLPHs7wthrzj5Gw2xk4X90PyiyG86FS2k62CRA z6rjEUki3uR0XPGxTyr8mSzODbA1mqml0HLNhkZawS0xW9Bw9qmD0y9hcPpbLyGxYZQorWZFN kAzVZkUSWvLPT6ZOYYhnyQ/u9sLYqmYhCTy2WoxLrfwmoEmQhMRUA1/c/IjMAcVya34WkPlOB fe8SJ43R01QfEQdvyuUXiiwKIKzDDz1Igyg3ThxmfSMHSVaiTHWY9NzawAx/9SVBtQ2O8KK2K il7/bZQyeCOk1IFNYYDiyg17ZSJOQEYes4LE97poSPVkAazTsQyOREfcI9K8pKUi+rs3Gv1li fuCmCgYz0Vad+IxTdgltTSEPr8z/N4Ec6ZosREuJa6QzZ0AyD3mACQNuPXD35cL3hutBJ7z30 4zpud6aGipumyqUkv6ZN7edDEnVAHeIrn1UOAmytM8pG2+sHS8HVCRAXxC/dTTdo5IrwV2F2n L9NYMLzU/MBCzwXjbO5mFOqzvleJXhAimiGVgAaXJaN4zFKbc8ABeUT2uz1qvKC7JUW7iO/+l QaWZCj/Q+ATV1a82h24VUsfEF7KgHTS1Be84kScIH9m0nVlG1BNDflcSNywee0yTvbbi1phlx aAIL+hTjmzYgViWMyDgfXQsmqNCveKwu64oWRKXFW2LUOkUk18eAJNGZo7ucbvHmgYIRISNBU fLPhOP2cuZ4cpdDdAi01fgRBMl6v1apE3wnlsIojRmhsKwOM6shy5tDzxCo2tyVp+lcwlGN1C 4enIYkdyAUB/Qh8Pt22Y2C/8NVkaP6IU3BLA8KEd7k04hiMjTmkJyJzFwIPrTyep+4GN2k+rg AzjurROXUncZ0TOHYnIhewP3ijSXYvbFpPOS5BITuenmvyby4tlh5oP3tYpEzfWQt3+x0f7iv yqVSBbxgbN7TRQLcf Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" From: Philippe Mathieu-Daud=C3=A9 Invalid I/O writes can craft an offset out of the vram_buffer range. Instead of passing an unsafe pointer to artist_rop8(), pass the vram_buffer= and the offset. We can now check if the offset is in range before accessing it. We avoid: Program terminated with signal SIGSEGV, Segmentation fault. 284 *dst &=3D ~plane_mask; (gdb) bt #0 0x000056367b2085c0 in artist_rop8 (s=3D0x56367d38b510, dst=3D0x7f9f97= 2fffff , val=3D0 '\0= 00') at hw/display/artist.c:284 #1 0x000056367b209325 in draw_line (s=3D0x56367d38b510, x1=3D-20480, y1= =3D-1, x2=3D0, y2=3D17920, update_start=3Dtrue, skip_pix=3D-1, max_pix=3D-1= ) at hw/display/artist.c:646 Reported-by: LLVM libFuzzer Buglink: https://bugs.launchpad.net/qemu/+bug/1880326 Signed-off-by: Philippe Mathieu-Daud=C3=A9 Signed-off-by: Helge Deller --- hw/display/artist.c | 40 +++++++++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 15 deletions(-) diff --git a/hw/display/artist.c b/hw/display/artist.c index a206afe641..47de17b9e9 100644 --- a/hw/display/artist.c +++ b/hw/display/artist.c @@ -273,11 +273,20 @@ static artist_rop_t artist_get_op(ARTISTState *s) return (s->image_bitmap_op >> 8) & 0xf; } -static void artist_rop8(ARTISTState *s, uint8_t *dst, uint8_t val) +static void artist_rop8(ARTISTState *s, struct vram_buffer *buf, + int offset, uint8_t val) { - const artist_rop_t op =3D artist_get_op(s); - uint8_t plane_mask =3D s->plane_mask & 0xff; + uint8_t plane_mask; + uint8_t *dst; + + if (offset < 0 || offset >=3D buf->size) { + qemu_log_mask(LOG_GUEST_ERROR, + "rop8 offset:%d bufsize:%u\n", offset, buf->size); + return; + } + dst =3D buf->data + offset; + plane_mask =3D s->plane_mask & 0xff; switch (op) { case ARTIST_ROP_CLEAR: @@ -375,7 +384,7 @@ static void vram_bit_write(ARTISTState *s, int posx, in= t posy, bool incr_x, for (i =3D 0; i < pix_count; i++) { uint32_t off =3D offset + pix_count - 1 - i; if (off < buf->size) { - artist_rop8(s, p + off, + artist_rop8(s, buf, off, (data & 1) ? (s->plane_mask >> 24) : 0); } data >>=3D 1; @@ -395,7 +404,7 @@ static void vram_bit_write(ARTISTState *s, int posx, in= t posy, bool incr_x, s->vram_bitmask & (1 << (28 + i))) { uint32_t off =3D offset + 3 - i; if (off < buf->size) { - artist_rop8(s, p + off, data8[ROP8OFF(i)]); + artist_rop8(s, buf, off, data8[ROP8OFF(i)]); } } } @@ -424,10 +433,10 @@ static void vram_bit_write(ARTISTState *s, int posx, = int posy, bool incr_x, if (!(s->image_bitmap_op & 0x20000000) || (vram_bitmask & mask)) { if (data & mask) { - artist_rop8(s, p + offset + i, s->fg_color); + artist_rop8(s, buf, offset + i, s->fg_color); } else { if (!(s->image_bitmap_op & 0x10000002)) { - artist_rop8(s, p + offset + i, s->bg_color); + artist_rop8(s, buf, offset + i, s->bg_color); } } } @@ -505,7 +514,7 @@ static void block_move(ARTISTState *s, int source_x, in= t source_y, int dest_x, if (dst + column > buf->size || src + column > buf->size) { continue; } - artist_rop8(s, buf->data + dst + column, buf->data[src + colum= n]); + artist_rop8(s, buf, dst + column, buf->data[src + column]); } } @@ -546,7 +555,7 @@ static void fill_window(ARTISTState *s, int startx, int= starty, offset =3D y * s->width; for (x =3D startx; x < startx + width; x++) { - artist_rop8(s, buf->data + offset + x, color); + artist_rop8(s, buf, offset + x, color); } } artist_invalidate_lines(buf, starty, height); @@ -559,7 +568,6 @@ static void draw_line(ARTISTState *s, int x1, int y1, i= nt x2, int y2, uint8_t color; int dx, dy, t, e, x, y, incy, diago, horiz; bool c1; - uint8_t *p; trace_artist_draw_line(x1, y1, x2, y2); @@ -628,16 +636,18 @@ static void draw_line(ARTISTState *s, int x1, int y1,= int x2, int y2, color =3D artist_get_color(s); do { + int ofs; + if (c1) { - p =3D buf->data + x * s->width + y; + ofs =3D x * s->width + y; } else { - p =3D buf->data + y * s->width + x; + ofs =3D y * s->width + x; } if (skip_pix > 0) { skip_pix--; } else { - artist_rop8(s, p, color); + artist_rop8(s, buf, ofs, color); } if (e > 0) { @@ -771,10 +781,10 @@ static void font_write16(ARTISTState *s, uint16_t val) for (i =3D 0; i < 16; i++) { mask =3D 1 << (15 - i); if (val & mask) { - artist_rop8(s, buf->data + offset + i, color); + artist_rop8(s, buf, offset + i, color); } else { if (!(s->image_bitmap_op & 0x20000000)) { - artist_rop8(s, buf->data + offset + i, s->bg_color); + artist_rop8(s, buf, offset + i, s->bg_color); } } } -- 2.21.3