scsi: ufs: core: tracing: Do not dereference pointers in TP_printk()

The trace events in drivers/ufs/core/ufs_trace.h were converted to take
a pointer to the hba structure as an argument for the tracepoint and
then in TP_printk() the printing of the dev_name from the ring buffer
was converted to using the dev dereferenced pointer from the hba saved
pointer.

This is not allowed as the TP_printk() is executed at the time the trace
event is read from /sys/kernel/tracing/trace file. That can happen
literally, seconds, minutes, hours, weeks, days, or even months later!
There is no guarantee that the hba pointer will still exist by the time
it is dereferenced when the "trace" file is read.

Instead, save the device name from the hba pointer at the time the
tracepoint is called and place it into the ring buffer event. Then the
TP_printk() can read the name directly from the ring buffer and remove
the possibility that it will read a freed pointer and crash the kernel.

This was detected when testing the trace event code that looks for
TP_printk() parameters doing illegal derferences[1]

[1] https://lore.kernel.org/all/20260630184836.74d477b6@gandalf.local.home/

Cc: stable@vger.kernel.org
Fixes: 583e518e7100 ("scsi: ufs: core: Add hba parameter to trace events")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://patch.msgid.link/20260630185412.283c26c5@gandalf.local.home
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/ufs/core/ufs_trace.h b/drivers/ufs/core/ufs_trace.h
index 309ae51b4906396ed3e5d68b98a0c0dc26e67ae4..377a3c54b9f56e0e0e859f8554d7047cbad79ec0 100644 (file)
--- a/drivers/ufs/core/ufs_trace.h
+++ b/drivers/ufs/core/ufs_trace.h
@@ -89,16 +89,18 @@ TRACE_EVENT(ufshcd_clk_gating,
 
        TP_STRUCT__entry(
                __field(struct ufs_hba *, hba)
+               __string(dev_name, dev_name(hba->dev))
                __field(int, state)
        ),
 
        TP_fast_assign(
+               __assign_str(dev_name);
                __entry->hba = hba;
                __entry->state = state;
        ),
 
        TP_printk("%s: gating state changed to %s",
-               dev_name(__entry->hba->dev),
+               __get_str(dev_name),
                __print_symbolic(__entry->state, UFSCHD_CLK_GATING_STATES))
 );
 
@@ -111,6 +113,7 @@ TRACE_EVENT(ufshcd_clk_scaling,
 
        TP_STRUCT__entry(
                __field(struct ufs_hba *, hba)
+               __string(dev_name, dev_name(hba->dev))
                __string(state, state)
                __string(clk, clk)
                __field(u32, prev_state)
@@ -119,6 +122,7 @@ TRACE_EVENT(ufshcd_clk_scaling,
 
        TP_fast_assign(
                __entry->hba = hba;
+               __assign_str(dev_name);
                __assign_str(state);
                __assign_str(clk);
                __entry->prev_state = prev_state;
@@ -126,7 +130,7 @@ TRACE_EVENT(ufshcd_clk_scaling,
        ),
 
        TP_printk("%s: %s %s from %u to %u Hz",
-               dev_name(__entry->hba->dev), __get_str(state), __get_str(clk),
+               __get_str(dev_name), __get_str(state), __get_str(clk),
                __entry->prev_state, __entry->curr_state)
 );
 
@@ -138,16 +142,18 @@ TRACE_EVENT(ufshcd_auto_bkops_state,
 
        TP_STRUCT__entry(
                __field(struct ufs_hba *, hba)
+               __string(dev_name, dev_name(hba->dev))
                __string(state, state)
        ),
 
        TP_fast_assign(
                __entry->hba = hba;
+               __assign_str(dev_name);
                __assign_str(state);
        ),
 
        TP_printk("%s: auto bkops - %s",
-               dev_name(__entry->hba->dev), __get_str(state))
+               __get_str(dev_name), __get_str(state))
 );
 
 DECLARE_EVENT_CLASS(ufshcd_profiling_template,
@@ -158,6 +164,7 @@ DECLARE_EVENT_CLASS(ufshcd_profiling_template,
 
        TP_STRUCT__entry(
                __field(struct ufs_hba *, hba)
+               __string(dev_name, dev_name(hba->dev))
                __string(profile_info, profile_info)
                __field(s64, time_us)
                __field(int, err)
@@ -165,13 +172,14 @@ DECLARE_EVENT_CLASS(ufshcd_profiling_template,
 
        TP_fast_assign(
                __entry->hba = hba;
+               __assign_str(dev_name);
                __assign_str(profile_info);
                __entry->time_us = time_us;
                __entry->err = err;
        ),
 
        TP_printk("%s: %s: took %lld usecs, err %d",
-               dev_name(__entry->hba->dev), __get_str(profile_info),
+               __get_str(dev_name), __get_str(profile_info),
                __entry->time_us, __entry->err)
 );
 
@@ -200,6 +208,7 @@ DECLARE_EVENT_CLASS(ufshcd_template,
                __field(s64, usecs)
                __field(int, err)
                __field(struct ufs_hba *, hba)
+               __string(dev_name, dev_name(hba->dev))
                __field(int, dev_state)
                __field(int, link_state)
        ),
@@ -208,13 +217,14 @@ DECLARE_EVENT_CLASS(ufshcd_template,
                __entry->usecs = usecs;
                __entry->err = err;
                __entry->hba = hba;
+               __assign_str(dev_name);
                __entry->dev_state = dev_state;
                __entry->link_state = link_state;
        ),
 
        TP_printk(
                "%s: took %lld usecs, dev_state: %s, link_state: %s, err %d",
-               dev_name(__entry->hba->dev),
+               __get_str(dev_name),
                __entry->usecs,
                __print_symbolic(__entry->dev_state, UFS_PWR_MODES),
                __print_symbolic(__entry->link_state, UFS_LINK_STATES),
@@ -279,6 +289,7 @@ TRACE_EVENT(ufshcd_command,
        TP_STRUCT__entry(
                __field(struct scsi_device *, sdev)
                __field(struct ufs_hba *, hba)
+               __string(dev_name, dev_name(&sdev->sdev_dev))
                __field(enum ufs_trace_str_t, str_t)
                __field(unsigned int, tag)
                __field(u32, doorbell)
@@ -291,6 +302,7 @@ TRACE_EVENT(ufshcd_command,
        ),
 
        TP_fast_assign(
+               __assign_str(dev_name);
                __entry->sdev = sdev;
                __entry->hba = hba;
                __entry->str_t = str_t;
@@ -307,7 +319,7 @@ TRACE_EVENT(ufshcd_command,
        TP_printk(
                "%s: %s: tag: %u, DB: 0x%x, size: %d, IS: %u, LBA: %llu, opcode: 0x%x (%s), group_id: 0x%x, hwq_id: %d",
                show_ufs_cmd_trace_str(__entry->str_t),
-               dev_name(&__entry->sdev->sdev_dev), __entry->tag,
+               __get_str(dev_name), __entry->tag,
                __entry->doorbell, __entry->transfer_len, __entry->intr,
                __entry->lba, (u32)__entry->opcode, str_opcode(__entry->opcode),
                (u32)__entry->group_id, __entry->hwq_id
@@ -322,6 +334,7 @@ TRACE_EVENT(ufshcd_uic_command,
 
        TP_STRUCT__entry(
                __field(struct ufs_hba *, hba)
+               __string(dev_name, dev_name(hba->dev))
                __field(enum ufs_trace_str_t, str_t)
                __field(u32, cmd)
                __field(u32, arg1)
@@ -331,6 +344,7 @@ TRACE_EVENT(ufshcd_uic_command,
 
        TP_fast_assign(
                __entry->hba = hba;
+               __assign_str(dev_name);
                __entry->str_t = str_t;
                __entry->cmd = cmd;
                __entry->arg1 = arg1;
@@ -340,7 +354,7 @@ TRACE_EVENT(ufshcd_uic_command,
 
        TP_printk(
                "%s: %s: cmd: 0x%x, arg1: 0x%x, arg2: 0x%x, arg3: 0x%x",
-               show_ufs_cmd_trace_str(__entry->str_t), dev_name(__entry->hba->dev),
+               show_ufs_cmd_trace_str(__entry->str_t), __get_str(dev_name),
                __entry->cmd, __entry->arg1, __entry->arg2, __entry->arg3
        )
 );
@@ -353,6 +367,7 @@ TRACE_EVENT(ufshcd_upiu,
 
        TP_STRUCT__entry(
                __field(struct ufs_hba *, hba)
+               __string(dev_name, dev_name(hba->dev))
                __field(enum ufs_trace_str_t, str_t)
                __array(unsigned char, hdr, 12)
                __array(unsigned char, tsf, 16)
@@ -361,6 +376,7 @@ TRACE_EVENT(ufshcd_upiu,
 
        TP_fast_assign(
                __entry->hba = hba;
+               __assign_str(dev_name);
                __entry->str_t = str_t;
                memcpy(__entry->hdr, hdr, sizeof(__entry->hdr));
                memcpy(__entry->tsf, tsf, sizeof(__entry->tsf));
@@ -369,7 +385,7 @@ TRACE_EVENT(ufshcd_upiu,
 
        TP_printk(
                "%s: %s: HDR:%s, %s:%s",
-               show_ufs_cmd_trace_str(__entry->str_t), dev_name(__entry->hba->dev),
+               show_ufs_cmd_trace_str(__entry->str_t), __get_str(dev_name),
                __print_hex(__entry->hdr, sizeof(__entry->hdr)),
                show_ufs_cmd_trace_tsf(__entry->tsf_t),
                __print_hex(__entry->tsf, sizeof(__entry->tsf))
@@ -384,16 +400,18 @@ TRACE_EVENT(ufshcd_exception_event,
 
        TP_STRUCT__entry(
                __field(struct ufs_hba *, hba)
+               __string(dev_name, dev_name(hba->dev))
                __field(u16, status)
        ),
 
        TP_fast_assign(
                __entry->hba = hba;
+               __assign_str(dev_name);
                __entry->status = status;
        ),
 
        TP_printk("%s: status 0x%x",
-               dev_name(__entry->hba->dev), __entry->status
+               __get_str(dev_name), __entry->status
        )
 );