Reading pixels from a bmp file in RISC-V assembly [RARS]

Question

I'm trying to access a bmp file using RARS and I have a problem with accessing pixels of it.

I'm trying to find a black pixel in my bitmap image but the way I did it gives me address out of range error when loading a byte from t3 to t5. Therefore I am pretty sure that I did something wrong with accessing data.

.data

FileName: .space 64
width: .space 320
height: .space 240
buf: .space 54

.text

#reading what is the file name
ReadingFileName:
    
    li a7, 8
    la a0, FileName
    li a1, 64
    ecall 
    
    la t0, FileName
    li t1, '\n'
    
FindEndOfString:
    lbu t2, (t0)
    beq t1, t2, RemoveN
    addi t0, t0, 1
    j FindEndOfString
    
RemoveN:
    li t1, '\0'
    sb t1, (t0)
    
#Reading data from file     
ReadingData:    
    #open the file
    li a7, 1024
    la a0, FileName
    li a1, 0
    ecall   
    
    #file descriptor
    mv s0, a0
    
    #check if file was opened correctly
    bltz s0, OpeningError
    
    #read data from file
    li a7, 63
    mv a0, s0
    la a1, buf
    li a2, 54
    ecall
    
    beq zero, a0, FileClose
    
    lw s1, buf
    addi s1, s1, 54 #start of pixels

FileClose:
    li a7, 57
    mv a0, s0
    ecall   

Main:
    li t1, 0 #first column of black pixels
    li t2, 0 #last column of black pixels
    mv t3, s1 #start of pixels
    
LookForBlackPixel:
    lbu t5, (t3)
    beqz t5, BlackPixelFound
    addi t3, t3, 1
    j LookForBlackPixel

BlackPixelFound:
    
OpeningError:
    

The error: Runtime exception at 0x00400094: address out of range 0x84364d78