fix load of large PPM images from a pipe

jcupitt · jcupitt · commit e19acd514853 · 2021-05-05T17:29:50.000+01:00
large PPM images loaded over pipes could cause a crash, thanks ewelot see #2240
diff --git a/ChangeLog b/ChangeLog
@@ -1,5 +1,6 @@
 30/4/21 start 8.10.7
 - better vips7 PNG load compatibility [SkyDiverCool]
+- fix load of large PPM images from a pipe [ewelot]
 
 22/12/20 start 8.10.6
 - don't seek on bad file descriptors [kleisauke]
diff --git a/libvips/foreign/ppmload.c b/libvips/foreign/ppmload.c
@@ -506,8 +506,8 @@ vips_foreign_load_ppm_generate_binary( VipsRegion *or,
 		while( n_bytes > 0 ) {
 			gint64 bytes_read;
 
-			bytes_read = vips_source_read( ppm->source, 
-				q, sizeof_line );
+			bytes_read = 
+				vips_source_read( ppm->source, q, n_bytes );
 			if( bytes_read < 0 ) 
 				return( -1 );
 			if( bytes_read == 0 ) {
@@ -516,8 +516,8 @@ vips_foreign_load_ppm_generate_binary( VipsRegion *or,
 				return( -1 );
 			}
 
-			n_bytes -= bytes_read;
 			q += bytes_read;
+			n_bytes -= bytes_read;
 		}
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -506,8 +506,8 @@ vips_foreign_load_ppm_generate_binary( VipsRegion *or,`
`506`	`506`	`while( n_bytes > 0 ) {`
`507`	`507`	`gint64 bytes_read;`
`508`	`508`
`509`		`- bytes_read = vips_source_read( ppm->source,`
`510`		`- q, sizeof_line );`
	`509`	`+ bytes_read =`
	`510`	`+ vips_source_read( ppm->source, q, n_bytes );`
`511`	`511`	`if( bytes_read < 0 )`
`512`	`512`	`return( -1 );`
`513`	`513`	`if( bytes_read == 0 ) {`
`@@ -516,8 +516,8 @@ vips_foreign_load_ppm_generate_binary( VipsRegion *or,`
`516`	`516`	`return( -1 );`
`517`	`517`	`}`
`518`	`518`
`519`		`- n_bytes -= bytes_read;`
`520`	`519`	`q += bytes_read;`
	`520`	`+ n_bytes -= bytes_read;`
`521`	`521`	`}`
`522`	`522`	`}`
`523`	`523`