Avoid float to int cast UB in exif

nikic · nikic · commit daf1fc6e316d · 2019-10-09T17:33:29.000+02:00
diff --git a/ext/exif/exif.c b/ext/exif/exif.c
@@ -4598,8 +4598,9 @@ PHP_FUNCTION(exif_read_data)
 		exif_iif_add_fmt(&ImageInfo, SECTION_COMPUTED, "CCDWidth", "%dmm", (int)ImageInfo.CCDWidth);
 	}
 	if(ImageInfo.ExposureTime>0) {
-		if(ImageInfo.ExposureTime <= 0.5) {
-			exif_iif_add_fmt(&ImageInfo, SECTION_COMPUTED, "ExposureTime", "%0.3F s (1/%d)", ImageInfo.ExposureTime, (int)(0.5 + 1/ImageInfo.ExposureTime));
+		float recip_exposure_time = 0.5f + 1.0f/ImageInfo.ExposureTime;
+		if (ImageInfo.ExposureTime <= 0.5 && recip_exposure_time < INT_MAX) {
+			exif_iif_add_fmt(&ImageInfo, SECTION_COMPUTED, "ExposureTime", "%0.3F s (1/%d)", ImageInfo.ExposureTime, (int) recip_exposure_time);
 		} else {
 			exif_iif_add_fmt(&ImageInfo, SECTION_COMPUTED, "ExposureTime", "%0.3F s", ImageInfo.ExposureTime);
 		}

Original file line number	Diff line number	Diff line change
`@@ -4598,8 +4598,9 @@ PHP_FUNCTION(exif_read_data)`
`4598`	`4598`	`exif_iif_add_fmt(&ImageInfo, SECTION_COMPUTED, "CCDWidth", "%dmm", (int)ImageInfo.CCDWidth);`
`4599`	`4599`	`}`
`4600`	`4600`	`if(ImageInfo.ExposureTime>0) {`
`4601`		`- if(ImageInfo.ExposureTime <= 0.5) {`
`4602`		`- exif_iif_add_fmt(&ImageInfo, SECTION_COMPUTED, "ExposureTime", "%0.3F s (1/%d)", ImageInfo.ExposureTime, (int)(0.5 + 1/ImageInfo.ExposureTime));`
	`4601`	`+ float recip_exposure_time = 0.5f + 1.0f/ImageInfo.ExposureTime;`
	`4602`	`+ if (ImageInfo.ExposureTime <= 0.5 && recip_exposure_time < INT_MAX) {`
	`4603`	`+ exif_iif_add_fmt(&ImageInfo, SECTION_COMPUTED, "ExposureTime", "%0.3F s (1/%d)", ImageInfo.ExposureTime, (int) recip_exposure_time);`
`4603`	`4604`	`} else {`
`4604`	`4605`	`exif_iif_add_fmt(&ImageInfo, SECTION_COMPUTED, "ExposureTime", "%0.3F s", ImageInfo.ExposureTime);`
`4605`	`4606`	`}`