| Message ID | 7fb0049c-c650-9f1a-bf9d-77b5d40e61af@googlemail.com |
|---|---|
| State | Accepted |
| Headers | show |
On Thu, Nov 10, 2016 at 08:52:29PM +0100, Andreas Cadhalpun wrote: > On 10.11.2016 02:26, Michael Niedermayer wrote: > > On Wed, Nov 09, 2016 at 10:46:03PM +0100, Andreas Cadhalpun wrote: > >> pnmdec.c | 4 ++++ > >> 1 file changed, 4 insertions(+) > >> a970cb981be02ea692d0bf2e68976077f14f2de3 0001-pnmdec-make-sure-v-is-capped-by-maxval.patch > >> From f315a3cfe35377a2638dc2294200a288408dc784 Mon Sep 17 00:00:00 2001 > >> From: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com> > >> Date: Wed, 9 Nov 2016 01:09:35 +0100 > >> Subject: [PATCH] pnmdec: make sure v is capped by maxval > >> > >> Otherwise put_bits can be called with a value that doesn't fit in the > >> sample_len, causing an assertion failure. > >> --- > >> libavcodec/pnmdec.c | 4 ++++ > >> 1 file changed, 4 insertions(+) > >> > >> diff --git a/libavcodec/pnmdec.c b/libavcodec/pnmdec.c > >> index ca97cc3..0f6a895 100644 > >> --- a/libavcodec/pnmdec.c > >> +++ b/libavcodec/pnmdec.c > >> @@ -144,6 +144,10 @@ static int pnm_decode_frame(AVCodecContext *avctx, void *data, > >> } else { > >> /* read a sequence of digits */ > >> do { > >> + if (v > (INT_MAX - c) / 10 || 10 * v + c > s->maxval) { > >> + av_log(avctx, AV_LOG_ERROR, "value 10 * %d + %d larger than maxval %d\n", v, c, s->maxval); > >> + return AVERROR_INVALIDDATA; > >> + } > > > > this test should nt be inside the loop > > you can try to benchmark with START/STOP_TIMER to see what effect > > this has (i didnt try but i expect it to be bad), this is the > > innermost loop of the decoder > > > > you can just unroll the loop by 5, thats the max number of iterations > > i think, which avoids the overflow > > it also should make the code faster > > Done, new patch attached. > > > iam reading in man ppm and others: > > "The maximum color value (Maxval), again in ASCII decimal. Must be less than 65536" > > Indeed, I'll send a separate match limiting maxval. > > Best regards, > Andreas > > pnmdec.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > 0dd61abddc422dd2ac37356f8271822d7e801b8e 0001-pnmdec-make-sure-v-is-capped-by-maxval.patch > From 2d402d8a38223b8c3c58d3e71e734932c9bdadae Mon Sep 17 00:00:00 2001 > From: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com> > Date: Wed, 9 Nov 2016 01:09:35 +0100 > Subject: [PATCH] pnmdec: make sure v is capped by maxval > > Otherwise put_bits can be called with a value that doesn't fit in the > sample_len, causing an assertion failure. LGTM thx [...]
On 11.11.2016 02:03, Michael Niedermayer wrote: > On Thu, Nov 10, 2016 at 08:52:29PM +0100, Andreas Cadhalpun wrote: >> pnmdec.c | 10 +++++++--- >> 1 file changed, 7 insertions(+), 3 deletions(-) >> 0dd61abddc422dd2ac37356f8271822d7e801b8e 0001-pnmdec-make-sure-v-is-capped-by-maxval.patch >> From 2d402d8a38223b8c3c58d3e71e734932c9bdadae Mon Sep 17 00:00:00 2001 >> From: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com> >> Date: Wed, 9 Nov 2016 01:09:35 +0100 >> Subject: [PATCH] pnmdec: make sure v is capped by maxval >> >> Otherwise put_bits can be called with a value that doesn't fit in the >> sample_len, causing an assertion failure. > > LGTM Pushed. Best regards, Andreas
From 2d402d8a38223b8c3c58d3e71e734932c9bdadae Mon Sep 17 00:00:00 2001 From: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com> Date: Wed, 9 Nov 2016 01:09:35 +0100 Subject: [PATCH] pnmdec: make sure v is capped by maxval Otherwise put_bits can be called with a value that doesn't fit in the sample_len, causing an assertion failure. --- libavcodec/pnmdec.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/libavcodec/pnmdec.c b/libavcodec/pnmdec.c index ca97cc3..958c5e4 100644 --- a/libavcodec/pnmdec.c +++ b/libavcodec/pnmdec.c @@ -43,7 +43,7 @@ static int pnm_decode_frame(AVCodecContext *avctx, void *data, int buf_size = avpkt->size; PNMContext * const s = avctx->priv_data; AVFrame * const p = data; - int i, j, n, linesize, h, upgrade = 0, is_mono = 0; + int i, j, k, n, linesize, h, upgrade = 0, is_mono = 0; unsigned char *ptr; int components, sample_len, ret; @@ -143,10 +143,14 @@ static int pnm_decode_frame(AVCodecContext *avctx, void *data, v = (*s->bytestream++)&1; } else { /* read a sequence of digits */ - do { + for (k = 0; k < 5 && c <= 9; k += 1) { v = 10*v + c; c = (*s->bytestream++) - '0'; - } while (c <= 9); + } + if (v > s->maxval) { + av_log(avctx, AV_LOG_ERROR, "value %d larger than maxval %d\n", v, s->maxval); + return AVERROR_INVALIDDATA; + } } if (sample_len == 16) { ((uint16_t*)ptr)[j] = (((1<<sample_len)-1)*v + (s->maxval>>1))/s->maxval; -- 2.10.2