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Fix improper mmap length paramater which can result in improper behavior

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or cmp crashing in specific cases.
This commit is contained in:
Brian Feldman 1999-07-29 23:26:22 +00:00
parent a243da2bc6
commit ac02226555
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=49235
1 changed files with 9 additions and 7 deletions
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16
usr.bin/cmp/regular.c
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@ -60,6 +60,7 @@ c_regular(fd1, file1, skip1, len1, fd2, file2, skip2, len2)
off_t byte, length, line;
int dfound;
off_t pagemask, off1, off2;
size_t pagesize;
if (sflag && len1 != len2)
exit(1);
@ -71,7 +72,8 @@ c_regular(fd1, file1, skip1, len1, fd2, file2, skip2, len2)
eofmsg(file2);
len2 -= skip2;
pagemask = (off_t)getpagesize() - 1;
pagesize = getpagesize();
pagemask = (off_t)pagesize - 1;
off1 = ROUNDPAGE(skip1);
off2 = ROUNDPAGE(skip2);
@ -79,15 +81,15 @@ c_regular(fd1, file1, skip1, len1, fd2, file2, skip2, len2)
if (length > SIZE_T_MAX)
return (c_special(fd1, file1, skip1, fd2, file2, skip2));
if ((p1 = (u_char *)mmap(NULL,
(size_t)length, PROT_READ, MAP_SHARED, fd1, off1)) == (u_char *)MAP_FAILED)
if ((p1 = (u_char *)mmap(NULL, (size_t)len1 + skip1 % pagesize,
PROT_READ, MAP_SHARED, fd1, off1)) == (u_char *)MAP_FAILED)
err(ERR_EXIT, "%s", file1);
madvise(p1, length, MADV_SEQUENTIAL);
if ((p2 = (u_char *)mmap(NULL,
(size_t)length, PROT_READ, MAP_SHARED, fd2, off2)) == (u_char *)MAP_FAILED)
madvise(p1, len1 + skip1 % pagesize, MADV_SEQUENTIAL);
if ((p2 = (u_char *)mmap(NULL, (size_t)len2 + skip2 % pagesize,
PROT_READ, MAP_SHARED, fd2, off2)) == (u_char *)MAP_FAILED)
err(ERR_EXIT, "%s", file2);
madvise(p2, length, MADV_SEQUENTIAL);
madvise(p2, len2 + skip2 % pagesize, MADV_SEQUENTIAL);
dfound = 0;
p1 += skip1 - off1;