title: IB/hfi1: Fix sdma.h tx->num_descs off-by-one error
description: In the Linux kernel, the following vulnerability has been resolved:
IB/hfi1: Fix sdma.h tx->num_descs off-by-one error
Unfortunately the commit `fd8958efe877` introduced another error
causing the `descs` array to overflow. This reults in further crashes
easily reproducible by `sendmsg` system call.
[ 1080.836473] general protection fault, probably for non-canonical address 0x400300015528b00a: 0000 [#1] PREEMPT SMP PTI
[ 1080.869326] RIP: 0010:hfi1_ipoib_build_ib_tx_headers.constprop.0+0xe1/0x2b0 [hfi1]
--
[ 1080.974535] Call Trace:
[ 1080.976990]  <TASK>
[ 1081.021929]  hfi1_ipoib_send_dma_common+0x7a/0x2e0 [hfi1]
[ 1081.027364]  hfi1_ipoib_send_dma_list+0x62/0x270 [hfi1]
[ 1081.032633]  hfi1_ipoib_send+0x112/0x300 [hfi1]
[ 1081.042001]  ipoib_start_xmit+0x2a9/0x2d0 [ib_ipoib]
[ 1081.046978]  dev_hard_start_xmit+0xc4/0x210
--
[ 1081.148347]  __sys_sendmsg+0x59/0xa0
crash> ipoib_txreq 0xffff9cfeba229f00
struct ipoib_txreq {
txreq = {
list = {
next = 0xffff9cfeba229f00,
prev = 0xffff9cfeba229f00
},
descp = 0xffff9cfeba229f40,
coalesce_buf = 0x0,
wait = 0xffff9cfea4e69a48,
complete = 0xffffffffc0fe0760 <hfi1_ipoib_sdma_complete>,
packet_len = 0x46d,
tlen = 0x0,
num_desc = 0x0,
desc_limit = 0x6,
next_descq_idx = 0x45c,
coalesce_idx = 0x0,
flags = 0x0,
descs = {{
qw = {0x8024000120dffb00, 0x4}  # SDMA_DESC0_FIRST_DESC_FLAG (bit 63)
}, {
qw = {  0x3800014231b108, 0x4}
}, {
qw = { 0x310000e4ee0fcf0, 0x8}
}, {
qw = {  0x3000012e9f8000, 0x8}
}, {
qw = {  0x59000dfb9d0000, 0x8}
}, {
qw = {  0x78000e02e40000, 0x8}
}}
},
sdma_hdr =  0x400300015528b000,  <<< invalid pointer in the tx request structure
sdma_status = 0x0,                   SDMA_DESC0_LAST_DESC_FLAG (bit 62)
complete = 0x0,
priv = 0x0,
txq = 0xffff9cfea4e69880,
skb = 0xffff9d099809f400
}
If an SDMA send consists of exactly 6 descriptors and requires dword
padding (in the 7th descriptor), the sdma_txreq descriptor array is not
properly expanded and the packet will overflow into the container
structure. This results in a panic when the send completion runs. The
exact panic varies depending on what elements of the container structure
get corrupted. The fix is to use the correct expression in
_pad_sdma_tx_descs() to test the need to expand the descriptor array.
With this patch the crashes are no longer reproducible and the machine is
stable.
affected:
{
product: Linux
vendor: Linux
defaultStatus: unaffected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: d1c1ee052d25, lessThan: 115b7f3bc1dc, status: affected, versionType: git
version: 40ac5cb6cbb0, lessThan: 5833024a9856, status: affected, versionType: git
version: 6cf8f3d690bb, lessThan: 3f38d22e645e, status: affected, versionType: git
version: bd57756a7e43, lessThan: 47ae64df23ed, status: affected, versionType: git
version: eeaf35f4e3b3, lessThan: 52dc9a7a573d, status: affected, versionType: git
version: fd8958efe877, lessThan: a2fef1d81bec, status: affected, versionType: git
version: fd8958efe877, lessThan: 9034a1bec35e, status: affected, versionType: git
version: fd8958efe877, lessThan: e6f57c688191, status: affected, versionType: git
}
{
product: Linux
vendor: Linux
defaultStatus: affected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: 6.3, status: affected
version: 0, lessThan: 6.3, status: unaffected, versionType: custom
version: 4.19.308, lessThanOrEqual: 4.19.*, status: unaffected, versionType: custom
version: 5.4.270, lessThanOrEqual: 5.4.*, status: unaffected, versionType: custom
version: 5.10.211, lessThanOrEqual: 5.10.*, status: unaffected, versionType: custom
version: 5.15.150, lessThanOrEqual: 5.15.*, status: unaffected, versionType: custom
version: 6.1.80, lessThanOrEqual: 6.1.*, status: unaffected, versionType: custom
version: 6.6.19, lessThanOrEqual: 6.6.*, status: unaffected, versionType: custom
version: 6.7.7, lessThanOrEqual: 6.7.*, status: unaffected, versionType: custom
version: 6.8, lessThanOrEqual: *, status: unaffected, versionType: original_commit_for_fix
}
