Author: kp Date: Fri Apr 29 20:19:41 2016 New Revision: 298799 URL: https://svnweb.freebsd.org/changeset/base/298799
Log: MFC r298664 msdosfs: Prevent buffer overflow when expanding win95 names In win2unixfn() we expand Windows 95 style long names. In some cases that requires moving the data in the nbp->nb_buf buffer backwards to make room. That code failed to check for overflows, leading to a stack overflow in win2unixfn(). We now check for this event, and mark the entire conversion as failed in that case. This means we present the 8 character, dos style, name instead. PR: 204643 Differential Revision: https://reviews.freebsd.org/D6015 Modified: stable/10/sys/fs/msdosfs/direntry.h stable/10/sys/fs/msdosfs/msdosfs_conv.c Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/fs/msdosfs/direntry.h ============================================================================== --- stable/10/sys/fs/msdosfs/direntry.h Fri Apr 29 20:13:35 2016 (r298798) +++ stable/10/sys/fs/msdosfs/direntry.h Fri Apr 29 20:19:41 2016 (r298799) @@ -145,7 +145,7 @@ struct msdosfsmount; char *mbnambuf_flush(struct mbnambuf *nbp, struct dirent *dp); void mbnambuf_init(struct mbnambuf *nbp); -void mbnambuf_write(struct mbnambuf *nbp, char *name, int id); +int mbnambuf_write(struct mbnambuf *nbp, char *name, int id); int dos2unixfn(u_char dn[11], u_char *un, int lower, struct msdosfsmount *pmp); int unix2dosfn(const u_char *un, u_char dn[12], size_t unlen, u_int gen, Modified: stable/10/sys/fs/msdosfs/msdosfs_conv.c ============================================================================== --- stable/10/sys/fs/msdosfs/msdosfs_conv.c Fri Apr 29 20:13:35 2016 (r298798) +++ stable/10/sys/fs/msdosfs/msdosfs_conv.c Fri Apr 29 20:19:41 2016 (r298799) @@ -678,7 +678,9 @@ win2unixfn(nbp, wep, chksum, pmp) switch (code) { case 0: *np = '\0'; - mbnambuf_write(nbp, name, (wep->weCnt & WIN_CNT) - 1); + if (mbnambuf_write(nbp, name, + (wep->weCnt & WIN_CNT) - 1) != 0) + return -1; return chksum; case '/': *np = '\0'; @@ -696,7 +698,9 @@ win2unixfn(nbp, wep, chksum, pmp) switch (code) { case 0: *np = '\0'; - mbnambuf_write(nbp, name, (wep->weCnt & WIN_CNT) - 1); + if (mbnambuf_write(nbp, name, + (wep->weCnt & WIN_CNT) - 1) != 0) + return -1; return chksum; case '/': *np = '\0'; @@ -714,7 +718,9 @@ win2unixfn(nbp, wep, chksum, pmp) switch (code) { case 0: *np = '\0'; - mbnambuf_write(nbp, name, (wep->weCnt & WIN_CNT) - 1); + if (mbnambuf_write(nbp, name, + (wep->weCnt & WIN_CNT) - 1) != 0) + return -1; return chksum; case '/': *np = '\0'; @@ -728,7 +734,8 @@ win2unixfn(nbp, wep, chksum, pmp) cp += 2; } *np = '\0'; - mbnambuf_write(nbp, name, (wep->weCnt & WIN_CNT) - 1); + if (mbnambuf_write(nbp, name, (wep->weCnt & WIN_CNT) - 1) != 0) + return -1; return chksum; } @@ -1030,7 +1037,7 @@ mbnambuf_init(struct mbnambuf *nbp) * This only penalizes portions of substrings that contain more than * WIN_CHARS bytes when they are first encountered. */ -void +int mbnambuf_write(struct mbnambuf *nbp, char *name, int id) { char *slot; @@ -1041,7 +1048,7 @@ mbnambuf_write(struct mbnambuf *nbp, cha printf("msdosfs: non-decreasing id: id %d, last id %d\n", id, nbp->nb_last_id); #endif - return; + return (EINVAL); } /* Will store this substring in a WIN_CHARS-aligned slot. */ @@ -1052,17 +1059,24 @@ mbnambuf_write(struct mbnambuf *nbp, cha #ifdef MSDOSFS_DEBUG printf("msdosfs: file name length %zu too large\n", newlen); #endif - return; + return (ENAMETOOLONG); } /* Shift suffix upwards by the amount length exceeds WIN_CHARS. */ - if (count > WIN_CHARS && nbp->nb_len != 0) + if (count > WIN_CHARS && nbp->nb_len != 0) { + if ((id * WIN_CHARS + count + nbp->nb_len) > + sizeof(nbp->nb_buf)) + return (ENAMETOOLONG); + bcopy(slot + WIN_CHARS, slot + count, nbp->nb_len); + } /* Copy in the substring to its slot and update length so far. */ bcopy(name, slot, count); nbp->nb_len = newlen; nbp->nb_last_id = id; + + return (0); } /* _______________________________________________ svn-src-stable-10@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-stable-10 To unsubscribe, send any mail to "svn-src-stable-10-unsubscr...@freebsd.org"
