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lavc/bmp: Avoid a heap buffer overwrite for 1bpp input.

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Found by Mingi Cho, Seoyoung Kim, and Taekyoung Kwon
of the Information Security Lab, Yonsei University.

(cherry picked from commit 1e34014010dba9325fc5430934b51a61a5007c63)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Carl Eugen Hoyos 2019-03-26 13:32:11 +01:00 committed by Michael Niedermayer
parent 0b93f59318
commit 8d3764a54d
1 changed files with 4 additions and 1 deletions
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5
libavcodec/bmp.c
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@ -286,7 +286,7 @@ static int bmp_decode_frame(AVCodecContext *avctx,
case 1: case 1:
for (i = 0; i < avctx->height; i++) { for (i = 0; i < avctx->height; i++) {
int j; int j;
for (j = 0; j < n; j++) { for (j = 0; j < avctx->width >> 3; j++) {
ptr[j*8+0] = buf[j] >> 7; ptr[j*8+0] = buf[j] >> 7;
ptr[j*8+1] = (buf[j] >> 6) & 1; ptr[j*8+1] = (buf[j] >> 6) & 1;
ptr[j*8+2] = (buf[j] >> 5) & 1; ptr[j*8+2] = (buf[j] >> 5) & 1;
@ -296,6 +296,9 @@ static int bmp_decode_frame(AVCodecContext *avctx,
ptr[j*8+6] = (buf[j] >> 1) & 1; ptr[j*8+6] = (buf[j] >> 1) & 1;
ptr[j*8+7] = buf[j] & 1; ptr[j*8+7] = buf[j] & 1;
} }
for (j = 0; j < (avctx->width & 7); j++) {
ptr[avctx->width - (avctx->width & 7) + j] = buf[avctx->width >> 3] >> (7 - j) & 1;
}
buf += n; buf += n;
ptr += linesize; ptr += linesize;
} }