CVE-2024-50151

In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix OOBs when building SMB2_IOCTL request

When using encryption, either enforced by the server or when using 'seal' mount option, the client will squash all compound request buffers down for encryption into a single iov in smb2setnext_command().

SMB2ioctlinit() allocates a small buffer (448 bytes) to hold the SMB2IOCTL request in the first iov, and if the user passes an input buffer that is greater than 328 bytes, smb2setnextcommand() will end up writing off the end of @rqst->iov[0].iov_base as shown below:

mount.cifs //srv/share /mnt -o ...,seal ln -s $(perl -e "print('a')for 1..1024") /mnt/link

BUG: KASAN: slab-out-of-bounds in smb2setnext_command.cold+0x1d6/0x24c [cifs] Write of size 4116 at addr ffff8881148fcab8 by task ln/859

CPU: 1 UID: 0 PID: 859 Comm: ln Not tainted 6.12.0-rc3 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014 Call Trace: <TASK> dumpstacklvl+0x5d/0x80 ? smb2setnextcommand.cold+0x1d6/0x24c [cifs] printreport+0x156/0x4d9 ? smb2setnext_command.cold+0x1d6/0x24c [cifs] ? __virtaddrvalid+0x145/0x310 ? __physaddr+0x46/0x90 ? smb2setnextcommand.cold+0x1d6/0x24c [cifs] kasanreport+0xda/0x110 ? smb2setnextcommand.cold+0x1d6/0x24c [cifs] kasancheckrange+0x10f/0x1f0 __asanmemcpy+0x3c/0x60 smb2setnextcommand.cold+0x1d6/0x24c [cifs] smb2compoundop+0x238c/0x3840 [cifs] ? kasansavetrack+0x14/0x30 ? kasansavefreeinfo+0x3b/0x70 ? vfssymlink+0x1a1/0x2c0 ? do_symlinkat+0x108/0x1c0 ? __pfxsmb2compoundop+0x10/0x10 [cifs] ? kmemcachefree+0x118/0x3e0 ? cifsgetwritablepath+0xeb/0x1a0 [cifs] smb2getreparse_inode+0x423/0x540 [cifs] ? __pfxsmb2getreparseinode+0x10/0x10 [cifs] ? rcuiswatching+0x20/0x50 ? __kmallocnoprof+0x37c/0x480 ? smb2createreparsesymlink+0x257/0x490 [cifs] ? smb2createreparsesymlink+0x38f/0x490 [cifs] smb2createreparsesymlink+0x38f/0x490 [cifs] ? __pfxsmb2createreparsesymlink+0x10/0x10 [cifs] ? findheldlock+0x8a/0xa0 ? hlock_class+0x32/0xb0 ? __buildpathfromdentryoptionalprefix+0x19d/0x2e0 [cifs] cifssymlink+0x24f/0x960 [cifs] ? __pfxmakevfsuid+0x10/0x10 ? __pfxcifssymlink+0x10/0x10 [cifs] ? makevfsgid+0x6b/0xc0 ? genericpermission+0x96/0x2d0 vfssymlink+0x1a1/0x2c0 dosymlinkat+0x108/0x1c0 ? __pfxdosymlinkat+0x10/0x10 ? strncpyfromuser+0xaa/0x160 __x64syssymlinkat+0xb9/0xf0 dosyscall64+0xbb/0x1d0 entrySYSCALL64afterhwframe+0x77/0x7f RIP: 0033:0x7f08d75c13bb