Write segments to core dump files in maximally-sized chunks that neither

exceed vn_rdwr_inchunks()'s INT_MAX length limitation nor span a block
boundary. This fixes dumping segments larger than 2GB.

PR:	67546

1 files changed, 21 insertions, 8 deletions

diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index e0b27c0..799fff1 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -37,6 +37,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/imgact.h>
 #include <sys/imgact_elf.h>
 #include <sys/kernel.h>
+#include <sys/limits.h>
 #include <sys/lock.h>
 #include <sys/malloc.h>
 #include <sys/mutex.h>
@@ -961,23 +962,35 @@ __elfN(coredump)(td, vp, limit)
 	/* Write the contents of all of the writable segments. */
 	if (error == 0) {
 		Elf_Phdr *php;
-		off_t offset;
+		off_t chunksize, offset, segofs;
 		int i;
 
 		php = (Elf_Phdr *)((char *)hdr + sizeof(Elf_Ehdr)) + 1;
 		offset = hdrsize;
 		for (i = 0; i < seginfo.count; i++) {
-			error = vn_rdwr_inchunks(UIO_WRITE, vp,
-			    (caddr_t)(uintptr_t)php->p_vaddr,
-			    php->p_filesz, offset, UIO_USERSPACE,
-			    IO_UNIT | IO_DIRECT, cred, NOCRED, (int *)NULL,
-			    curthread); /* XXXKSE */
-			if (error != 0)
-				break;
+			/*
+			 * Write the segment in maximally-sized chunks that
+			 * neither exceed vn_rdwr_inchunks()'s INT_MAX
+			 * length limitation nor span a block boundary.
+			 */
+			segofs = 0;
+			while (segofs < php->p_filesz) {
+				chunksize = MIN(php->p_filesz - segofs,
+				    INT_MAX - MAXBSIZE + 1);
+				error = vn_rdwr_inchunks(UIO_WRITE, vp,
+				    (caddr_t)(uintptr_t)php->p_vaddr + segofs,
+				    chunksize, offset + segofs, UIO_USERSPACE,
+				    IO_UNIT | IO_DIRECT, cred, NOCRED,
+				    (int *)NULL, curthread); /* XXXKSE */
+				if (error != 0)
+					goto done;
+				segofs += chunksize;
+			}
 			offset += php->p_filesz;
 			php++;
 		}
 	}
+done:
 	free(hdr, M_TEMP);
 
 	return (error);